Wonder how close you can get two parts together, and still have it able to move and not fuse together during the print?

Here's a simple test for that! The distance between the parts is 0.1mm for the tightest, and 0.6mm for the loosest. (0.05mm ~ 0.3mm for the tighter one (files v21).)

If you can move the little arm (with the lever), you can get away with that clearance! If you can but it requires some force on the first try to unstuck it... You can use it, but probably best to use a slightly bigger clearance. If you can't move it, well then that's probably a too tight tolerance.