What you need (but you can modify the list):
-used 35mm film cartridge (plus container if needed)
-IKEA paper measure tape
-alcohol pencil (or similar)
-a bigger container (eg sauce container)
Step 1: Create the Logbook
First, use the glue to attach the measure tape to the tiny piece of film remaining in the cartridge (remember to put adhesive tape in the back to reinforce the connection)
Step 2: Secure the Other End
Then, attach the toothpick to the other end of the tape (use glue, staples and a piece of tape to reinforce). Cut the excess.
Step 3: Identify It
Write "logbook" in the cartridge. Just in case...
Step 4: Finalize
Use the film container (optional), then place your new logbook in the Geocache container, together with the pencil and some minor stuff, as usual, and place it in its hidding place. Don't forget the stashnote! Happy geocaching!