Advanced Inset

Blender 3.3 – 5.2 · Windows, macOS and Linux · no engine required

An inset whose corners never collapse. Every rounded or chamfered corner becomes a handle you can push to its own depth, widen, or give more vertices — all before you confirm. The same editor also works on corners the mesh already has, with nothing inset at all.

It appears in Blender's add-on list as Tachyon Advanced Inset, so it groups with the other Tachyon Studio tools there.

Getting started

The problem it solves

Blender's inset is a parallel offset: every boundary vertex slides inward along the bisector of its two edges. On a straight edge that is exactly right. On a rounded corner — a fan of short edges — every bisector points at the arc's centre, so the arc shrinks as it goes in: a corner of radius r inset by t has radius r − t. At t = r the whole fan lands on one point, and past it the vertices cross over and the corner turns inside out. That is the wrecked corner you have seen on beveled ngons.

Measured on a 0.5-radius corner: fine at 0.4, a single point at 0.5, inverted at 0.6.

How it works

Using the editor

Press Shift + Alt + I with faces selected and the whole inset follows the mouse. Click once and it becomes an editor:

With nothing selected, every edit applies to all corners at once. The panel at the bottom of the viewport carries the same actions as clickable chips, and reads back the selection, distance, spread, segment count and mode as you work. H shows or hides the full list of shortcuts.

The bare mouse wheel is left alone — it stays Blender's zoom, as everywhere else. Corners are picked rather than dragged, because their handles sit on the mesh and a pointer reaching for one should not move it.

Sides

A side follows its corners until you give it a depth of its own. Click its dot and use Shift + Wheel or I, or drag the dot, and that side goes in less or more than the rest — a shallow inset along the long sides of a panel and a deep one across its ends, say. The corners at its two ends slide to where the two offset edges now cross, so nothing tears. A selects all the corners; a side is only ever picked on purpose.

Nothing can cross

Three caps, and a corner is held by whichever is tightest:

The readout says (at limit) while a corner is being held back.

When two corners stop against each other, the two vertices that met are left exactly touching and welded into one on confirm — no sliver of an edge left between them.

You can turn the whole thing off with C if you want to see what would have happened.

Spread

Ctrl + Wheel widens or tightens the selected corner. This changes the corner's radius about the point where its two straight edges would meet if the corner were sharp, so the tangent points slide along those edges and stay on them — which is what "rounder" and "tighter" mean to a modeller. Scaling about the arc's own centre would lift its ends off the edges.

S resets the selection's spread to ×1, and U switches between giving every selected corner the same length (Absolute) or the same multiple of its own size (Relative).

Segments

Alt + Wheel doubles or halves the selected corner's vertex count, and Ctrl + Alt + Wheel changes it one vertex at a time.

New vertices land on the fitted circle, so adding them makes the corner rounder rather than a finer version of the same chords. A corner that is a single sharp vertex takes a count too: it is replaced by a run along a fillet tangent to the two edges meeting there. Only the inset arc changes: the outer arc and the rest of the mesh are untouched, and the rim between them is rebuilt end to end — quads where the counts allow, triangles where they do not, carrying the rim's material, smoothing and UVs.

Auto Merge

M turns on the alternative to being held back. Nothing is capped; instead the outline is swept inward as a straight skeleton, and whenever two vertices meet they become one vertex that carries on along the bisector of the two edges left either side of it.

So a rounded corner pushed too deep is eaten one vertex at a time until it is the sharp corner underneath, and pushed further still two corners fuse into one. Everything that remains sits exactly where a plain offset of the surviving shape would put it, so the outline stays clean rather than creased. Confirming welds the coincident vertices.

It is off by default, because the cap is the safer default.

Merge and Split corners

J makes the selected neighbouring corners into one corner: a single arc tangent to both flanks, reaching as far as the old corners did, with the vertices spaced evenly along it. The end of a slab becomes a semicircle; the bottom of a notch becomes a U; a V-notch becomes its fillet.

From then on it is one corner in every respect — one distance, one spread, one vertex count, one mode — and it stays selected so your next edit acts on it as a single piece. The merge survives changing its segments.

Shift + J splits a merged corner back into the corners it was made of, each keeping the merged distance.

Corner sensitivity

[ and ] change how long an edge has to be to count as a straight run — which is what decides where one corner ends and the next begins; Shift with them steps finely. The report line tells you how many corners the new setting found.

Use it when a corner is being read as two, or when a shallow bevel is not being recognised as a corner at all.

Copy and paste

Ctrl + C opens a list of what the selection carries — distance, spread, segment count, mode, and the options (Offset Even, Edge Rail, No Collapse, Auto Merge) — each with its current value beside a tick box. Tick what you want and press Copy. Where the selected corners disagree, the row says the first corner's value is the one taken.

Ctrl + V shows the same list holding what was copied, so you can paste only the distance, or only the spread and segments, onto whatever is selected now, or onto every corner with nothing selected.

• Spread is copied as a length, so the same number is the same size on any corner: 0.3 copied off a round corner is 0.3 on a filleted sharp one.
• The vertex count reads N vertices, and pastes onto any corner, including one that is still a single vertex, which becomes a round of that many vertices.

The clipboard outlives the editor. Copy in one inset, confirm, start the next and paste, and the settings carry over.

Quads, regions and Individual

One n-gon gets the corner solver described above. A quad, or more than one face, gets Blender's own inset for its positions — the only thing that is right in 3D on a selection that wraps a corner — with the corner controls laid over it: every corner still has its handle, its own distance, spread and vertex count, and the sides their own depth. A rounded corner keeps its shape here too: under Keep Shape it moves as one piece in the plane of the face it was modelled in. T switches it to Shrink, which is Blender's offset exactly.

Edge Rail is off by default, as it is on Blender's own inset, so a quad or a region of faces insets exactly as I would. R turns it on.

Individual (the chip, or I while the inset is still following the mouse) insets every face on its own, as Blender's I-then-I does, each with its own corners.

Edit Corners

The same editor, on corners the mesh already has. Nothing is inset; what moves is the mesh itself. Shift + Alt + C, the toolbar, or the Face and Vertex menus.

The inset shortcut falls through to this when only vertices are selected, so one shortcut serves both.

Changing a corner's vertex count reconnects what was attached. Where the run has a parallel run beside it joined by a rail of quads — the far side of a bevel, the wall below a plate's top edge — that rail is rebuilt against the new count, quads where the counts allow and triangles where they do not. Otherwise the faces along the run simply take the new vertices.

Edge Rail and Auto Merge do not apply here and are not offered.

The menu

Shift + Alt + T opens the tools as a pie or a dropdown — whichever the preferences say. It carries:

• Inset (Editable) — this add-on's inset.
• Edit Corners — the editor with no inset.
• Blender Inset — Blender's own, unchanged, for when a plain parallel offset is exactly what you want.

Each entry can be switched off. Preferences ▸ Menu lists all three with a checkbox each.

Every control

Every key above except confirm and cancel can be changed in the add-on preferences, and any of them can take Ctrl, Shift or Alt (on a Mac, also Cmd, with Alt shown as Option). The ones that go up and down (the wheel rows and [ ]) can each be the wheel with any modifiers, or a pair of keys: one for up, one for down.

Preferences

Limits worth knowing

• Attribute interpolation (UVs, colours) on the rim is done by Blender at the starting distance. Push a corner much deeper and the UV stretch on that rim quad will not follow — the same behaviour as moving the vertices after a normal inset.
• Segments and Auto Merge are declined on Blender 3.3. Both change topology, and that build's bmesh is intermittently fatal at the Python teardown which follows such operator sequences — nothing in Python can prevent it. 3.4 and later are fine; everything else works on 3.3.
• The maths works in the plane of the region's average normal. On a strongly curved region the inset is an approximation, as any planar offset is.
• There is no redo panel. It would re-run the inset on geometry that is already inset and discard every per-corner edit, so the operator does not offer one. Ctrl + Z undoes the whole inset in a single step, and bpy.ops.tin.inset(thickness=...) still works from a script.
• Auto Merge handles vertices meeting each other. A concave vertex reaching a distant edge is not a merge event, so an asymmetric concave shape pushed absurdly deep with Auto Merge on can still self-cross; the caps cover that case when it is off.

Troubleshooting

Network use and files written

None, and almost none. The add-on opens no sockets, sends no telemetry and checks no licence. The Documentation and Discord buttons hand a URL to your default browser and nothing more.

Release history

Support

Questions, bug reports and feature requests — join the Discord. The same invite is in the add-on preferences, next to a link back to this documentation.

GPL-3.0-or-later. Copyright 2026 Tachyon Studio.