Here are two Add-ons:
Add Mesh Primitive: Round Cube. Documentation, download link and examples on Round Cube wiki page (updated to v0.3, unzip presets in scripts/presets directory)
Round Cube is a multi-purpose mesh primitive.
Being a mathematical sphere, the corners are not pinched, bevels are round, and polygon face sizes are more balanced (more uniform polygon surface area) than other methods (e.g. subdivision surface + cast or bevel modifiers).
The add-on can also produce any size (x, y, z) capsule or cuboid. One of the disadvantages to consider is that non-spherical objects produced by this add-on will not scale well non-uniformly after they are generated.
Hover over the operator parameters for a description of their use. Note resulting size is the largest of either radius (of vertices) or size (by axis).
UVs are easily created using the Follow Active Quads option to get a cross map.
One of the primary purposes for this add-on is to produce good primitives for sculpting.
Some example meshes it can generate:
I suggest using All for sculpting.
This add-on started from a much more simple Convex Hull Margin add-on I had written over a year ago but didn’t get around to releasing (I did release C++ code for Bullet). I decided to clean up the original and release it, but wasn’t sure if anyone would have any use for it, so I also took some time to write this more general purpose Round Cube one.
So the Convex Hull Margin add-on will produce an approximate convex hull either shrunk or expanded by a specified margin from a selected object, with, or without bevelling. For examples, see the following video; the bevelled collision margin visualizations are all expanded by a margin, i.e. 0.25 (you could use it to bevel a Cone, for example):
Bullet Physics Collision Margins and Shapes
Hopefully someone finds these useful. I’ll answer questions below.