Since I was doing a lot of height mapping for sprites in #DiceTrek, I decided to make a little "pillow shading" script in Aseprite. It helps to quickly create a "base" which I can then edit extra depth details into.
I figure other people might be able to use it, so here it is: https://github.com/RefresherTowel/Aseprite-PillowShading
And here's a little gif showing one of the ways I use it.