MagClamp

I saw these things online for at least 25 bucks (including magnets, but hey). I refuse to pay that amount of money for a couple simple pieces of plastic.

I also created one for round magnets but Thingiverse threw that out or something. This is a corner clamp with magnetic locking so you can glue in perfect 90 degree angles. Ideal for model building houses and so on.

This one features a magnet size of 8x2x3mm. I have not tested it yet with the size because my magnets are still en route. Anyway, the one with round magnets works like a charm.

Just add magnets the right way. Add glue if you want them to stick good, but I think it will work without just as well.

For completeness I added the ones for round magnets as well. I suggest testing the magnets to see which way they go in. I suggest you put them all in the same way (e.g. with magnetic poles the same side). Because for the Inner clamp of the round version (6mm diameter, 4.7mm height). YOU CANNOT GET THEM MAGNETS OUT! They'