A near year and a new monthly-ish project series: YoTA (year of technical art)! This work was done with Blender and Krita. There's no code at all this time, I'm just storing this on github because it's what I'm familiar with now. It's also on Sketchfab.
I was trying to model a small toy I bought for my cat, just for the sake of practicing 3D modeling. Since all the files are quite small, I've included everything - both the 3D model as well as the Krita files used to create the textures.
Modeling was done using the multiresolution modifier. This is similar to the subdivision surface modifier, but it allows you to sculpt on the higher density mesh. More importantly, after sculpting details on the higher multires mesh, it is very simple to 'bake' a normal map that mimics the surface normals of the high res mesh onto one of the lower res meshes. This makes it easy to create decent looking 'low-poly' versions of the model that look similar to the higher resolution mesh. I found this (very short) video tutorial especially helpful in understanding how to bake out the normal map: https://www.youtube.com/shorts/4WCuMszwM2U
The fluffy plush look was hard to mimic and I ended up going through multiple iterations trying to get the right look. Almost all attempts looked like some variation on an orange peel. I originally try to sculpt some bumps/ridges to get the fluffy look, but this didn't work well, possibly because my mesh wasn't dense enough, or maybe it's just a bad approach? While I don't think I quite got the plushy look, the approach I ended on was to texture paint (within Blender) noise onto a separate texture (which was multiplied in to the base color map), which I then saved out as a standalone texture. It's also used as a bump map, which seems to help sell the effect, though I think there's still a lot of room for improvement here.
The hi-res model used a bump map for both the fluffy texture as well as the stitching texture on the mouth and eyes of the model. This worked great in hi-res, but didn't seem to get baked in to the normal map when trying to make the low-poly model. I spent a lot of time fussing with trying to make a combined normal map using the baked normals + normals baked out from the fluff/stitching bump maps, and had a lot of trouble. It turns out, however, that bump node in Blender has a normal input. By passing the hi-res baked normals into this input, and the existing stitching/fluffy bumps maps in to the bump input, the result came out as expected, without all the confusing mess of trying to combine normal maps together. Good to know for future reference!