key hole slot (use as a negative space)

thingiverse

To hang a project on a wall, create a "keyhole" slot using a router bit in the woodworking style. This involves plunging the bit into the surface and moving along the piece. In 3D printing, use the "difference" operation or assign the "hole" color to this slot when grouped with your main object in Tinkercad. This method works well for wall hangings. The design is available at https://tinkercad.com/things/5rcAYD0KB15 for editing online.