The Password Plus wallets were a simpler design. They can be created from 3" x 5" index card stock and adhesive tape.
Take a 3" x 5" card oriented horizontally. Draw a line from the bottom left corner to a point 15/16" in from the upper left corner. Draw another line from the bottom right corner to a point 15/16" in from the upper right corner. Take another card and make a "sandwich" consisting of two cards. Cut along the lines you have drawn. This will give you two trapezoids 3" in height, 5" along the bottom aspect and 3 1/8" along the top aspect. Draw a vertical line from a point 15/16" in from the bottom left corner (directly below the top left corner of the trapezoid) and 15/16" in from the bottom right corner. Fold both cards along these lines. Apply tape along the 3 1/8" top aspect to form a hinge. Apply tape to the left and right aspects of the trapezoid so that, by squeezing the sides, the wallet will open.
For the passwords, cut some 3" x 5" cards in half. The result will be a series of cards measuring 3" x 2 1/2". The passwords are printed on these cards and fit inside the wallets. You can hold these cards in place with adhesive putty (the kind used to mount posters to a wall). This will enable you to remove the passwords and reuse the wallets. The process was more involved in 1979 but nowadays you can use a printer to print the passwords before cutting these cards in half. Alternatively, you could use very light-tack paper labels.
Once upon a time you could get small circular paper clips about the diameter of a dime. You could use these to keep the wallets closed and to hold the passwords in place. The wallets we used on the show were a little more elaborate in construction but this gives you the basic idea.
Let me know if my instructions need clarification.