EDIT: I have uploaded clamp without side chamfers for better printing.
I made this long L-bracket and Clamp (U-bracket) for mounting DIY table to wall.
This bracket is supposed to be used for short side of table, helping on one side while other side is held by regular table legs or is mounted to the wall as well.
Included with L-bracket STL model is Clamp for combining two sheets of wood together. It should be enough to use just screws, but if you want something, that will look better, I recommend using clamps. Clamp is made for 12mm high sheet of wood.
Drawing for L-bracket
Drawing for Clamp (U-bracket)
The author marked this model as their own original creation.