Slide the pointed end of a second unit into the pocket of the first.
If you are looking to make a paper project involving "twisting" and "zipping" (which the name suggests), How to Make a Modular "Twist-Zip" Cube Part 3- Twiszip
: Flip the piece over and fold the two pointed ends inward to form a perfect square with two flaps on the back. Repeat : Do this for all 6 pieces of paper. Assembling the Cube ("Part 3"): Take one unit and hold it so the "pockets" are facing you. Slide the pointed end of a second unit