Good News, everyone!!! I think I finally figured out a way to upload feet images from 3D model characters from https://www.deviantart.com/jcthornton who wear footwear. I use 3D Builder to take off their footwear and upload them to Print 3D/Paint 3D/3D Viewer and I can take photos from these websites onto DeviantArt/Fur Affinity. However, the quality of the models may not be the same as the other model characters who are usually barefooted, I'm afraid. But at least I can take requests on feet images of footwear 3D model characters such as Mickey Mouse, Minnie Mouse, Sandy Cheeks, etc.. Now you can request me any 3D model feet images of both barefooted characters and footwear characters at anytime!