I think MIXEL app used to do this until they changed their format. Muse app is close to what I want except for the customization.
I played with these ideas from my own sources of images in Sketchbook X (and Brushes app). It works, but there may already be an app that makes this easier. Any ideas?
Here is my finished file.
Then I pulled in pngs from my collection on layers that I could transform.