If I look sideways at my wrist and hold a tape measure in front of it, I see that it is about 4 cm thick. My fingers are even thinner, my ankles are about 6 cm thick. That is all solid enough in the real world not have broken in the last 50 years. However what happens if I scan myself in 3D with a laser scanner and start printing a horde of Tobolds for use in a tabletop game? The usual scale for tabletop D&D is "28 mm", which corresponds to the 1 inch square equals 5 feet scale of the battle map, which corresponds to a 60:1 miniaturization.

So I'm printing my imaginary army to Tobolds, armed with daggers and maces, and what happens? The wrists, ankles, daggers, mace handles all come out at 1 mm thickness or less, and that doesn't work well with a PLA filament printer. Either it doesn't even print right, or those spots are extremely thin and fragile. I could hardly remove the figurine from the printer bed without breaking it off at the ankles.

While I am not printing Tobolds, I do print miniatures of humans, humanoids, and monsters that I find on the internet. And a lot of them are "realistic", that is to say the dimensions of the body correspond to the dimensions of the artists drawings in the monster manual, which strive to make them look as real as possible. Some models are smaller and thinner than humans, lets say kobolds or elves, some are about the same, some are a bit sturdier. But unless I print an ogre, many of the things I print have this problem of having thin spots.

Some of the problems can be fixed. I can use Tinkercad to add bits and pieces to a model, so several of my models which were holding axes or maces are now holding axes or maces with unrealistically thick handles. But at least those print okay. But if I can find a monster model which is more cartoonish than realistic, it frequently will print a lot better in 3D. The cartoonish exaggeration and simplification of the body ends up with a lot less thin body parts.

One other method I am using is fattening the monsters myself. For example I take the model of the kobold and scale it up by a factor of two. Now the thickness is better, but it is too tall. So then I just change the scale in the Z-axis, while keeping the X- and Y- axis at their increased values. I end up with a kobold that looks a lot fatter than the drawing in the Monster Manual, but that I can print. Still there are a lot of monsters, like everything with tentacles or eye stalks that are really problematic for printing.