When I'm designing miniatures, I occasionally have to cut them into multiple parts so that they can be printed successfully. When I cut them, I like to make slots in the two parts of the mini, with a post to guide them together. My printer works great if the slot is .2 mm larger than the post, but other printers might be more precise or less precise, so I made this quick tolerance test to help figure out how much of a gap you need for this style of post!
The post is the same kind of trapezoid that I frequently use on my miniatures. The base has 6 slots in it, ranging from 0 mm of tolerance up to .5 mm (in increments of .1 mm). You'll probably need some tweezers to get the post into the slots, but this will tell you how much of a gap you'll need for this sort of post/slot design, so you can increase or decrease the size of posts in the future to make sure that you get a snug fit!