MESHmachine is a blender mesh modeling addon with a focus on hard surface work without subdivision surfaces.

Watch the trailer for an overview of all the tools in 0.6.
Or check out the written overview in the documentation.

turn chamfers into fillets/bevels and back
change the width of a chamfer or bevel
create variable fillets and washouts
unchamfer and unbevel to go back to a hard edge
practically edit existing existing bevels
resolve tricky geometry overlaps in cases where two bevels meet
flatten multiple polygons based on another polygon or flatten a single polygon based on 3 vertices
flatten along a normal or flatten along edges
redirect chamfer flow by turning the corners
convert triangular bevel corners into quad corners
plug details into your mesh
build your own plugs and create/buy/sell plug libraries
stash objects or face selections, creating backups, that can be brought back or referenced by other tools, without cluttering the scene
conveniently add boolean modifiers (incl. split booleans), create automatic stashes when applying the mods, and easily duplicate or instance objects using booleans
cleanup applied booleans and create clean perimeter loops around their intersections
create flattened, straightend, and transferred custom normals
symmetrize meshes including their custom normals
turn mirror modifiers into real objects
loop select, sharp select and vertex group select, all using a single keymap
easily add wedges
best documentation in the business