I have created bracket as table leg holder for 2x4 wood planks to build a big almost O shaped desk for all of my family members. The holders not only hold the legs in place but also connect the different boards of the desk (the built in “arrows” are helpful for alignment). There are many other possible uses beyond using them as table leg holders. After two years of heavy use by my family two (out of 15) broke (maybe because of sideways leverage force when someone ran into them). I made some adjustments that should make them stronger but even with two broken I'm still happy how they performed and the desk is really sturdy.

*Another possible cause why they broke could be that in the first version it was a bit of a too tight fit so that I had to hammer some of them on (the with of the planks vary slightly). In the new version, they are slightly wider allowing for a bit more tolerance. Having to hammer them on might have caused tension in the first place causing them to break more easily.

First round I printed in PLA, the new ones in PETG @ 0.3mm layer height and 15% infill. ABS might even perform better in durability.