Icons without letters
This proposal can be seen as an UI improvement idea. The first time I started Curvy 3D the icons with letters in them confused me a bit as I thought it would mean their shortcut. My proposal here is to get rid of the letters and instead change the icons a bit. For example, the icons of surface tools could integrate an stylized wireframe mesh, and the texture tools a classic checkerboard texture.
From this
to this
Vertex painting
Nothing fancy, but it would be nice to have, especially since it needs only very few resources and shouldn't be too hard to implement.
Clay brush
In Curvy 3D, with a "bulge" brush shape the Add brush can mimik the popular Clay brush which can be found in most sculpting programs (e. g. 3D Coat). But still, it's not the same! The Add brush in Curvy 3D - as its name implies - adds material to the surface every time you make a stroke. But it also continually adds material over the same stroke even when the mouse button wasn't released since then. A clay brush doesn't do that. Moreover, a Clay brush feels more natural since it applies new material in way that reminds of soft and ductile clay. So, I'd like to see a dedicated Clay brush to be implimented in the next version of Curvy 3D.
In Curvy 3D, the Add brush can quickly lead to oversized "overhangs" which are not only hard to rescuplt to a proper shape but also intruduce poor and jagged geometry oftenly.
For comparison: One of the few standard clay brushes found in 3D Coat.
Shape library
It would be nice to save custom brush shapes in a library for later use.
Live update of brush shape
When using this
shape control the shape of the brush should be visible and auto-updated in the 3d viewport.
Redo command
In the menu there is undo but no redo.
Voxel Merge Selection/Mask
A voxel merge function that can be restricted to certain areas of the model. Prevents existing geometry from being re-meshed by the voxel merge algorithm.
Cone primitive
So, we have Sphere, Cube, and Cylinder, but no Cone primitive?
Seriously, can be very useful sometimes.
Misc
I think you made accidently a typo here:
More ideas to come!