Blueprint Technical Drawings 1.0.0

Dimensioned 2D technical drawings from your meshes: views, section, hidden lines, dimensions, title block; export SVG, DXF and PDF at true scale. Blender 4.2 LTS or newer, tested on 4.2 LTS, 5.1 and 5.2 LTS.

Install

1. Extension (Blender 4.2+): download blueprint_drawings-1.0.0.zip, then Edit › Preferences › Get Extensions › the drop-down menu (top right) › Install from Disk, or drag the zip into Blender.
2. Legacy add-on zip: install blueprint_drawings-1.0.0-legacy.zip via Edit › Preferences › Add-ons › the drop-down menu (top right) › Install from Disk, then tick "Blueprint Technical Drawings".
3. Press N in the 3D Viewport and open the Blueprint tab.

Note: install one of the two zips, not both: a second copy registers nothing, says so in a popup and one console line, and Blender leaves it unticked.

Uninstall

Before you uninstall (recommended): in each .blend that used the add-on, click Remove Blueprint Data from This File (Blueprint tab › Help, or the add-on's Preferences) and save. It asks first and shows what goes.

• It deletes the preview sheets and their objects.
• It removes the Blueprint settings, manual dimensions and stored object lists from every scene of that file.
• Your own objects are not changed.

Then Edit › Preferences › Add-ons (or Get Extensions), find "Blueprint Technical Drawings", untick it and choose Uninstall / Remove. Every class, panel, handler and timer the add-on registered is removed.

What stays in files you did not clean:

• The Blueprint settings and manual dimensions, as scene data. A reinstall finds them again.
• The preview sheet objects (each with a small "blueprint_preview" tag, which copies of them keep), with the materials "Blueprint Paper" and "Blueprint Ink". Remove Preview deletes them while the add-on is installed.
• After an uninstall: in the Outliner, right-click the "Blueprint preview" collection › Delete Hierarchy. The sheet leaves the viewport; its objects and the two materials stay in the file, unseen (see One limit).
• To remove those too: install the add-on again, click Remove Blueprint Data from This File, save, then uninstall.
• The links to the objects you drew or dimensioned. They are normal Blender object links inside the scene's Blueprint data. The add-on never writes anything onto your objects.
• One limit: such a link counts as a user of the object or of the preview collection it points to.
• An object you delete after the uninstall stays in the file, unseen, while the link exists (the preview's objects too). Remove Blueprint Data before you uninstall avoids this.
• While the add-on is enabled it lets go of deleted objects and of a preview collection that is in no scene by itself: right after the delete, when a file is opened and when the add-on is enabled again.

Quick start

1. Select your mesh object(s) (Object Mode; in Edit Mode the current edit mesh is drawn).
2. Blueprint tab › Make Drawing. The preview sheet appears in the viewport, right of the model; View frames it from the top.
3. Adjust Sheet & Scale, Views & Lines, Section, Dimensions, Title Block; click Regenerate.
4. Export panel › Export. The report shows where the files went; the folder button opens it.

Panels and settings (defaults)

In a new scene only the main panel is shown: the sub-panels below appear after the first Make Drawing or a click on Edit Settings.

Preferences

Edit › Preferences › Add-ons › Blueprint Technical Drawings holds the defaults for new scenes: sheet, orientation, projection, style, units, decimals, company, drawn by, line widths, model units and export folder. A scene takes them when its first Make Drawing or Export finishes, or when you click Edit Settings; until then the panel says so. Opening, saving or editing a file, showing the Blueprint tab, an early error or Esc never write them into a scene. To apply them to a scene that already has settings, use Help › Load Preference Defaults. The Preferences also hold Max edges per view (200,000), the safety limit for very heavy meshes, and, like the Help panel, Remove Blueprint Data from This File (see Uninstall).

Layers (SVG groups, DXF layers, PDF layers)

The layer names are the usual CAD layer names (CENTER, HIDDEN as in AutoCAD's line types). All texts of the add-on use US spelling (center, color, gray, license), as Blender itself does.

Workflows

• 3D-print part for a customer: A4, Auto scale, first or third angle, Section on, material "PETG", export PDF.
• Laser / CNC plate: On a new scene, first click Edit Settings in the Blueprint panel; the settings panels then appear.
• Then: scale 1:1, units mm, turn off every view except the one you cut (usually Top), turn Section off, export DXF and use only its VISIBLE layer in your CAM software.
• The BORDER layer (the sheet frame with the ISO 5457 centering marks, at least 0.7 mm wide) and the title block are in the DXF and SVG too. Hide or delete BORDER, TEXT and DIM before cutting.
• Several parts in one drawing: select them all; neighboring parts get different hatch directions (45°, 135°, 60°, 150°, 30°, 120°, repeating).
• Rotated part: Axes › Active object, so front/top/right follow the part instead of the world.
• Imperial: Units › inch (dimensions with 3 decimals by default, DXF in inches); the sheet stays true scale.

How it works

For each view the add-on draws sharp edges (faces meeting at more than the feature angle), open boundaries and silhouettes. Visibility is tested with ray casts every sheet millimeter along each edge; where visibility changes the edge is split by bisection. Collinear pieces are merged and hidden lines lying under visible ones removed. For the files, lines are joined into polylines; line ends closer than 0.02 sheet mm are welded, so a closed outline is one closed path even on slightly uneven meshes. In the section view, edges behind the cut face (inside the material) are covered by it, as on a real section. Section outlines are oriented by the face normals and filled with the nonzero winding rule, so overlapping shells of one object are one solid (parts with flipped faces use even-odd). Holes are closed sharp edge loops of 12+ vertices that fit a circle within 1 %; a hole is labeled in a view only when ray casts just inside its rim are visible there.

Tips

• Hard-surface models: keep the feature angle at 30°. Bevels with only 2 segments (45° steps): raise it to 50° so the bevel facets are not drawn.
• Bevels with 3 or more segments (30° steps or less) already show only their outline.
• Stray lines on a flat face usually mean flipped normals: Mesh › Normals › Recalculate Outside. Lines along UV seams of an imported glTF / FBX / STL: Mesh › Clean Up › Merge by Distance.
• Print PDFs at 100 % / actual size. The PDF has one optional-content layer per line type (a viewer with a layers panel can hide them; we have not tested specific viewers).
• You can stay in Edit Mode: Make Drawing uses the current edit mesh. In Edit Mode, Ctrl+Z only steps back through mesh edits: leave Edit Mode before undoing a drawing or an added dimension.
• Low-poly holes are labeled from 12 segments up (also when the walls are sharper than the Feature angle). 6-, 8- and 10-sided pockets are treated as polygons, not holes.
• Laser / CNC: turn off every view except the one you cut (usually Top) and turn Section off, then export the DXF at 1:1 in mm and cut the VISIBLE layer only.
• Otherwise the VISIBLE layer holds the outlines of every view.
• The result box in the panel shows a short summary; the full message is in the Info editor (and the status bar).

Troubleshooting

Limits

• Meshes only: convert curves and text to mesh first; Geometry Nodes instances need a Realize Instances node. Collection instances, Verts / Faces instancing and particle instances of meshes are drawn. Non-mesh selected objects are skipped and counted in the report.
• Dimensions: overall sizes and hole diameters are automatic; there are no automatic hole-position dimensions. Manual dimensions are aligned (point to point) between two vertices, so a hole center without a vertex cannot be picked.
• The title block has no revision, sheet-number or tolerance fields: add those in your CAD program.
• The isometric view shows visible lines only and has no dimensions; the section view shows no hidden lines (drafting convention).
• Hole labels only in front, top or right views looking along the hole axis and showing its rim. Polygons with fewer than 12 sides are never holes; a 12-gon pocket is taken for a round hole.
• A chamfered rim gives one Ø (the bore); a counterbore, a countersink, a stepped bore, a thin tube and holes in two stacked parts keep both diameters.
• Sections: overlapping shells of one object are filled as one solid (nonzero rule); for an object with flipped faces the even-odd rule is used, so there an overlap stays unhatched (Recalculate Outside fixes it).
• Two interpenetrating parts are each hatched (crossed hatching in the overlap) and the report says so.
• Instances: at most 5,000 per drawing (the report says when more were skipped); Geometry Nodes instances are not drawn (Realize Instances).
• While a drawing runs only viewport navigation passes: mouse wheel, middle mouse, numpad, Ctrl+Space, and left clicks inside the 3D Viewport itself (navigation gizmo, Alt+click navigation, selecting).
• Clicks on menus, the sidebar or other editors and all other keyboard shortcuts, Ctrl+S included, wait until it is done. Esc cancels in the window that started the run; from another window use the Cancel button in the Blueprint panel.
• One drawing (one sheet) per scene; use another scene for a second drawing.
• Split vertices: meshes from glTF / FBX / some STL exporters can have split vertices along UV seams. The seams are then drawn as lines and sections are not hatched.
• Mesh › Clean Up › Merge by Distance fixes it (the report says so).
• ISO 129: an overall size that equals a labeled outer Ø is not repeated, also not in another view (a Ø90 flange gets no "90" width in its Front view).
• Tick Dimensions › Repeat in every view to show it anyway.
• DXF units: R12 has no official units field. The file is in mm (or inch with Units = inch); the newer $INSUNITS header value is written too (we have not tested which CAD programs use it).
• Line widths are kept in SVG and PDF; the DXF uses fixed layer colors (see Layers).
• Very noisy scans give busy drawings: raise the Feature angle or turn Hidden lines off. A per-view edge limit (Preferences) keeps huge meshes safe.
• Many hole sizes: at most 8 diameters per view get a Ø leader (the 8 largest); the report names the others ("… view: N hole diameters, Ø leaders on the 8 largest").
• The leaders are planned only at the scale the layout chose, with a fixed amount of work per plan, in steps (Esc works).
• When no position keeps every leader clear, the drawing is made with the fewest crossings and the report says so.
• Many holes: at most 500 holes per view get a center mark (a perforated sheet, a speaker grille).
• The Ø labels still count every hole, the DXF has every hole as a CIRCLE, and the report says when the limit was reached.
• In Edit Mode, modifiers whose Edit Mode display is off are left out (as you see them); the report says so. Tab to Object Mode to draw them.
• File not saved yet: Export writes into the shared home/Blueprint drawings folder and never overwrites a file there, whatever the Overwrite setting: a second "Cube" becomes "Cube (2)". Save the .blend to export next to it.
• Chain lines end with a long dash in the SVG, the PDF and the preview.
• In the DXF the pattern comes from the CENTER line type (R12 has no per-line pattern scale), so it is not fitted to each line.
• DXF R12 only (no lineweights in DXF). PDF title-block text supports Western European characters only (standard Helvetica font, no embedded fonts): Japanese, Cyrillic, Greek and other scripts become "?" in the PDF, and the export report says how many.
• Use the SVG for other scripts; it keeps every character.
• Visibility is sampled every sheet millimeter: an occluder thinner than that can be missed. With a very large total edge length (over 20 million samples per view) the spacing grows and the report says so.
• Long steps: on a multi-million-face mesh the longest single steps (Blender reading the mesh with its modifiers, one view's visibility pass) pause the window.
• Each takes up to about 2.5 s at 1.57 million faces, longer on bigger meshes (no redraw, Esc is read right after). Above 3 million faces the add-on first shows an estimate (time, pauses, memory) and asks.
• Undo, a file load or deleting the part in another window stops a running drawing cleanly. Repeat Last (Shift+R) starts the same stepped run again (progress bar, Esc), with the heavy-mesh question again above 3 million faces.
• Repeat History and the Adjust Last Operation panel do the same: an earlier answer is never reused. Running the operators from a Python script (bpy.ops) runs them to the end at once.
• The preview lines are loose mesh edges: they show in Solid and Wireframe shading with Overlays on (Overlays off, Material Preview or Rendered: only the blank sheet shows).
• A heavy preview (hundreds of thousands of edges) is stored in the .blend and in every undo step: click Remove Preview before saving to keep the file small.
• Loose edges use the theme wire color, so the preview always uses the Paper colors (Style only changes the SVG / PDF).
• Hole leaders keep clear of the rims and center marks of the other holes, of each other and their labels, of the dimension on the right and of the extension lines of manual dimensions.
• On a very crowded view (many holes at a small scale) that can be impossible: the report then says so, and a larger scale or sheet gives them room.
• Other texts can still touch on crowded views: move them in an SVG editor or your CAD program.
• Scenes made with Scene › New › Linked Copy share the "Blueprint preview" collection: a drawing made in one replaces the preview in the other.
• The last drawing is kept in memory for a quick Export (drawings over 3 million lines are not kept); it is freed when you open another file.
• Manual dimensions store the vertex positions when added; if you edit the mesh later, delete and add the dimension again (moving the object is fine).
• The points are the Edit Mode vertices (before modifiers, active shape key): on Array, Mirror or Boolean results a picked point is not always on the drawn geometry.
• Pick vertices that the modifiers leave in place, or apply them on a copy. Manual dimensions go outside their view.
• On each side of a view the overall and the manual dimensions are stacked by length (ISO 129-1): the shortest closest to the view, the overall dimension outermost, so no extension line crosses a dimension line.
• The layout keeps room for them.
• Two dimensions that overlap only partly (one starts inside the other and ends outside it) cannot avoid a crossing in one stack: the report says so (measure both from one common point, or pick one in another view).
• A dimension too short for its arrows between the extension lines has them outside; where an outside arrow would cross a neighbor's extension line, that end gets a dot instead (ISO 129-1).
• With dots at both ends the dimension has no tail, and its value stays over its middle (the outer extension lines leave a gap there).
• A diagonal dimension (two points not level with each other) is placed beyond the stack of its side, and the layout keeps room for it. Its extension lines can still cross other dimension lines: the report then says so.
• As in ISO 129-1, each extension line starts 1 mm from the point it measures (it may cross the outline) and is left open where it would run through a text.
• To dimension hole positions, pick the same rim point of two holes (e.g. both rightmost points) or a rim point on a hole's center line: the dimension is then drawn between the hole center lines, which are extended to it.
• Hole leaders are placed clear of these extension lines; when that is impossible the report says so.

FAQ

Is the PDF / SVG / DXF really at true scale?
Yes. The sheet is written in millimeters (SVG user units = mm, PDF page in points at 72 per inch, DXF in mm or inch). At 1:1 a 100 mm edge is 100 mm: 283.46 pt in the PDF. Print the PDF at 100 % / actual size, not 'fit to page'.

Does it use my modifiers?
Yes. It draws the evaluated mesh, as you see it in the viewport: Booleans, arrays, mirror, bevel, subdivision (in Edit Mode, modifiers hidden in Edit Mode are left out, with a note). Your mesh is never changed.

Can I use the DXF for laser cutting or CNC?
Yes. Set Scale to 1:1, units mm, turn off every view except the one you cut (usually Top) and turn Section off; otherwise the VISIBLE layer holds the outlines of every view. In your CAM program use the VISIBLE layer only and hide all others (BORDER, HIDDEN, SECTION, HATCH, CENTER, CUTLINE, DIM, TEXT). Outlines are joined, closed POLYLINEs (line ends closer than 0.02 mm are welded, so slightly uneven meshes from Booleans or STL files still give closed loops), and holes seen whole in that view are true CIRCLE entities (with Hole diameters on). Other curves (arcs, rounded corners, a hole partly hidden) are short straight segments, as fine as your mesh: use enough segments on curved edges, or fit arcs in your CAM program if it offers that. The file is plain DXF R12 (the plain ASCII format); our tests parse it back and check every entity, but we have not tested it in CAM programs, so try a small part first. On a new scene, first click Edit Settings in the Blueprint panel; the settings panels then appear.

Why are my hole diameters not labeled?
A hole is recognized when its rim is a closed loop of edges sharper than the Feature angle that forms a circle with at least 12 segments, and it is labeled in the view that looks along its axis and shows its rim (a vertical hole in the Top view). A single chamfer is fine (you get the bore Ø). A rounded rim (a multi-segment bevel or a fillet) has no edge sharper than the feature angle: lower the Feature angle below the angle between the fillet facets, or add a manual dimension. Shade Smooth and Mark Sharp do not matter. Holes at an angle to all three views are drawn but not labeled.

My model is an STL in millimeters but the numbers are 1000× too big or small.
Set Views & Lines › Model units to '1 unit = 1 mm'. On a new scene, first click Edit Settings in the Blueprint panel; the settings panels then appear. Scene units follows Scene › Units (Blender's default scene counts 1 unit as 1 meter); when a part comes out over 10 m or under 1 mm, the report suggests the right setting (if the size is right, set Model units explicitly, e.g. '1 unit = 1 m', and the note goes away).

How fast is it on heavy meshes?
About 12–17 seconds for our 1.57-million-face test mesh with 4 views, a section and hidden lines; the longest single pause of the window is up to about 2.5 s, and Blender peaked at about 1.6 GB of memory. It runs in steps with a progress bar: you can orbit, pan and zoom (mouse wheel, middle mouse, numpad, the navigation gizmo) and Esc in the window that started it (from another window: the Cancel button in the Blueprint panel) cancels: Make Drawing leaves nothing behind; Export canceled after its files were saved keeps the files it wrote. Time, pauses and memory grow with the face count: above 3 million faces the add-on shows an estimate and asks first. On very big scans turn Hidden lines off or decimate a copy.

Can the PDF show Japanese, Cyrillic or Greek text?
Not yet: PDF title-block text supports Western European characters only (the PDF uses the standard Helvetica font, without embedded fonts), so other scripts show as "?" in the PDF and the export report says how many. Use the SVG for other scripts: it keeps every character (UTF-8 text, checked by our tests). The DXF writes them as \U+ codes (the DXF way to write characters outside its code page; emoji, outside that range, become ?). We have not tested which CAD programs show these codes as characters.

First angle or third angle?
First angle (ISO, Europe and most of the world) puts the top view below the front view; third angle (ANSI, USA) puts it above. Pick it in Sheet & Scale, set your default in the Preferences. The title block shows the matching symbol.

Can I edit the drawing afterwards?
Yes: the files are plain vector drawings. The SVG has one group per line type, marked as a layer the way Inkscape stores layers (inkscape:groupmode="layer"); the DXF has one layer per line type, the PDF one optional-content layer per line type. Our tests check these groups and layers in the files; we have not tested how each program shows them. Changes in Blender? Click Regenerate and export again; all settings are kept.

Changelog

1.0.0 (2026-11-04): initial release (see the feature list above).

License

GPL-3.0-or-later. © 2026 Sonneblom Digitaal.