Open back Airtag mount and keychain

When you play sound on Apple Airtag the sound is transmitted through the back of the unit. I designed these with an open back to allow the sound to carry farther. Also, I added side-slots to one mount in case someone were to flush mount the tag to a flat surface to allow the sound to escape and carry farther.  Print with supports to have cleaner bolt holes. I haven't put the design through rough testing but I would print in PETG not PLA. Designed for M3 nuts and bolts or screws. If I get enough interest in this model i'll add the .step file later.