I thought I'd share my workflow as it pertains to the making of heads, hands, feet and other parts that are not related to any mechanical function. If you, like me, prefer making these kinds of parts by sculpting in clay rather than 3D modelling you may find it useful or interesting.
The first step after sculpting something out of clay is to digitize it, accomplished by either using photogrammetry (constructing a 3D mesh out of photos) or by using a 3D scanner. The photogrammetry route is typically cheaper but more time consuming and the results can vary greatly depending on camera, setup and software (there are good resources and tutorials available, for example the shakespeare scanner and OpenScan). Dedicated 3D scanning hardware is more expensive but is usually much faster with more reliable results. There are some scanners that aren't astronomically priced and still yield very good results, for example scanners from Revopoint.
Regardless of the approach some post processing is likely needed and usually just involves cleanup and smoothing. This can be done using the sculpting tools in Blender although I find those tools somewhat clunky and prefer to do post processing in virtual reality, using something like Masterpiece. Working with 3D in virtual reality is very intuitive and easy, although perhaps only feasable if you already have access to a virtual reality headset (I would not consider it worth it to obtain one for the sole purpose of doing 3D modelling). It's an interesting experience to make a small head in clay and then proceed to scale it to natural size (or larger) and stand face to face with it in VR.
When making hands it can be worthwhile to make use of the armature features in Blender. Normally used for animation, rigging a model with an armature allows for reposing. This essentially means that only one hand has to be sculpted in clay and scanned. After cleaning it can be rigged with an armature, posed, mirrored and then reposed again.
If using a blue light 3D scanner such as a Revopoint Pop Mini, which requires the sculpture you're scanning to be uniformly white (as opposed to textured, needed for photogrammetry) it can be worthwhile to use a modelling clay that does not harden such as plastiline. This way you really only need one piece of clay at all times. After having sculpted something you scan it and after that you can make something else out of the same piece of clay.
Skeleton hand sculpted by my wife.
A clay hand.
The sculpture is photographed from different angles, about 100 photos in total (with help of the shakespeare scanner).
The mesh is constructed in Meshlab.
Alternatively one can use a dedicated 3D scanner (scanner depicted in use is a Revopoint Pop Mini).
The mesh is cleaned and processed in VR using Masterpiece.
After cleaning you'll end up with a printable part.
If the part is a hand it can be rigged with an armature in Blender.
After rigging, a suitable pose is configured.
The hand can then be mirrored and reposed again.
After fitting the part to the rest of the puppet it can be printed.