I wanted a very minimal modular frame to hang my Instax pictures since sticky gum and tape would leave marks behind. Since I didn't find any, I made it myself.

This one you can make as long as you want vertically. The top piece hangs over an edge of the closet, table or anything you want. To keep it from falling off, add a piece of sticky gum or tape to keep the top piece in place. You can also just use a string. Tolerance is pretty tight so it may be a bit hard to link them the first time.

In the future I might add Square and Wide formats too.