3D Printing and At-Home Fabrication Tips

I just recently made my Gloomhaven Cave Bear model , which needs to be printed in two pieces because of the details around the bear's teeth.  When I was cutting the model to be printed, I realized that I was going to need a post to help guide the head into place (otherwise it was really difficult to line up the fur), which got me thinking about the whole post-and-slot design for situations like this. When I've done similar cuts in the past, I put the post directly on one half and cut the cavity into the other half... and that worked great, as long as I got my tolerances correct.  When I failed to get them right, I was stuck either reprinting the part with the post (after making the post slightly smaller) or the part with the cavity (after making it slightly larger).  Either way, I had to reprint a fair amount of the model.  I noticed this problem even more when I was printing a model that someone else had pre-cut.  He had cut it with a 5% tolerance, which so...

In my model cutting for 3d printing post, I mentioned that I like to use trapezoids for alignment keys.  Why is that?  6 axial alignment, bro. Ok, that phrase is a bit ridiculous, but when I took notes on my concept for this post, that's all I wrote down... and it's kindof true.  An isosceles trapezoid gives you keying on all 6 axes, whereas most other simple shapes (like squares, rectangles or circles) generally only provide absolute positions on 5 of them.  What am I talking about, when I mention 5 vs. 6 axes? Do you remember when the PS3 came out with its new Sixaxis controller?  At the time, I scoffed, thinking that we live in a 3 dimensional world and so there are only 3 axes, commonly called X, Y, and Z.  Therefore, this whole "six axis" thing was obviously just a marketing gimmick meant to make it sound more high tech.  Well, younger me was certainly wrong about that! I was  right that there are only 3 axes, but what I didn't think a...