Scrap cardboard (cut to the write size for your binder)
Step 1: Step 1
Add Duct Tape strips, covering the holes.
Step 2: Step 2
Using the previous holes as a guide, use the hole punch to cut through the duct tape.
You can now cover the holes, and do the same process with the other side to cut them.
Step 3: Step 3
If you want to add tabs:
Take a strip of duct tape and fold it halfway on itself.
Stick it to the back of your divider.