Jay, I primarily use Blender 3d.
Its a free 3d modeling program suite. You can model 3d objects, digitally sculpt, render images from the 3d models with several different render engines, create animations, create sound tracks plus many other things with it. It can be a little challenging to master due to all the things it is capable of doing but its free.
A very generous artist shared his custom compositor node setup which uses the 3d model depth information and ambient occlusion to create the depth maps. The blend file can be found in this thread.
https://blenderartists.org/t/two-cents/654804/27
In rare instances where it doesn't produce a good result I also try with Zbrush and my cnc design software (Carvewright Designer).