Fuji Instax uses a disposable case that contains 10 films. When your 10 shots are done, you remove the empty case and replace with a new deck.
This design is to simply reuse the cases by inserting the photos back and arrange them on the wall.. Coz those cases are pretty cool looking and would be quite a waste if just throwing them away..
Don't throw away those cases when one deck is finished.
Look at the end where the photos come out. A piece of tape-like thing (call it a layer) is blocking the "exit" where the photos come out from inside the case. Pare that layer up a little bit, until you can push a photo back inside.
Repeat step 2, then arrange your new photo frames as you like~