Keyhole hanger insert
thingiverse
These work great if you don't have a keyhole bit or if the project is fairly thin. They are 5mm deep and drilled out with a 1 1/8 forstner bit. Added a blank insert for velcro or hanging adhesive tape.
Download Model from thingiverse
With this file you will be able to print Keyhole hanger insert 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 Keyhole hanger insert.