Maybe these would be some help?

The majority of us use a mouse because it's actually easier than using a drawing tablet. I have a perfectly good large Intuos Pro, but I never use it with CC3 because mouse is better.

However, I get what you are saying since there are users who cannot use a mouse, though I am out of my depth regarding any kind of alternatives - not being a coder myself.

I gave in to temptation and warped a copy of the inner crater to the new grid. Looks like I also still have craters on the brain.

Oh well, I might as well carry on...

Here's a preview of the form using just the shading.

We have craters now :)