Bracket for clamping stuff together in a corner or 90 degree.

For either gluing or welding. For welding you might want to use ABS

Post-Printing

Just thread the three holes with m5 and insert a magnet and a m5 screw.

The magnets are 15mm in diameter and 4mm thick. The hole ist about 5mm. You can get them pretty cheap on eBay or Aliexpress