Locking piece
grabcad
With four such pieces printed together, it can become a self lock. Its from Solidedge, which I did long back....
Download Model from grabcad
With this file you will be able to print Locking piece with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Locking piece.