Use one color of Duck Tape to completely cover the Ziploc baggie. Make sure not to tape over the opening of the baggie, so it can still be used to store the pieces.
Place several strips of the other color of duct tape onto a sheet of wax paper. Cut 32 squares that are all the same size.
Peel from the wax paper like stickers and attach them evenly to the top of the baggie in alternating rows of four.
Cover twelve of your buttons with one color of tape, and twelve with the other color of tape. To cover the buttons, place a small square of tape over the top of the button.
Press the Duck Tape down and smooth, then use scissors to trim around the edges of the button; press down the remaining tape to give it a smooth top.
Store your buttons on the inside of the baggie for safe keeping.
Video
Notes
Step 1: Press out any bubbles, and cut your tape with straight lines. The Duck Tape can overlap if need be.