Update 5/22/20: Thanks to Lauren72 for pointing out that the last stl I posted doesn't match my final product. I just added a 4th version with numbers recessed rather than protruding. Enjoy!

Update 3/9/20: Made my first print of this model. It turned out about how I expected it would. I sliced in Cura 4.4 with supports touching build plate and support angle at 45 or 50 degrees? Printed on my ender 3 with a 0.2mm nozzle, 0.08 layer height. Top half looks pretty decent I think. Bottom isn't great, but I think it will clean up ok with some sanding.

It rolls with a nice wobbling, meandering kind of action and settles down pretty quickly if you roll it gently.

Update 3/6/20: Now with NUMBERS!!!!

Update 3/5/20: In d_one_hunnid-2 I flattened the faces a bit, getting it ready to add numbers.

This is my first upload to thingiverse. It is a 100-sided polyhedron. It will eventually be a d100 die that I intend to cast in pewter.

I constructed it in Blender by much brute force and manual placing of polygons and merging of points and filling of edge loops.

Is it very janky looking and not beautiful? Yes.
BUT... Is it a mathematically-designed, completely random, fair d100? No.
BUT... Will it print easily on an FDM printer? Probably not so much.
BUT... Will it be easy to read the outcome of a roll after I get the numbers on there? No chance.
BUT... Will it wobble around on the table and eventually stop somewhere causing much drama when the DM attempts to divine which number is actually facing up and thus what wild surge or fey effect or random encounter or what have you the party will have to deal with? That's my hope.

Feel free to use the files make your own almost useless random effect roller. Show me what you come up with if you do.