12 piece Burr puzzle with pins.
Six right handed and six left handed pieces are needed for this puzzle, it's not that difficult to figure out, but still an entertaining puzzle none the less. I included a 2 piece and a 4 piece design because when I tried to print more than 4 they warped too much by the time it was done printing. Either print 6 of the 2-piece stl, or 3 of the 4-piece stl, the sizes should be identical for the two stl files, so if it warps while printing 4 then try printing two at a time. Both stl files include an even number of right and left handed pieces.
Enjoy the puzzle!