029: Velcro vs. zippers.
If you're making costumes for a project, and you have the choice, use velcro instead of zippers. While velcro will lose its effectiveness over time, slowly getting less and less "sticky," a zipper will work perfectly until it breaks, and then it's 100 percent useless.
We ran into a broken zipper on one of our space suits last weekend before we'd even loaded the camera. As we didn't have a spare zipper on set, much less the time to install one, we solved the problem with safety pins* and careful selection of camera angles.
*Keep plenty of safety pins nearby when you're filming -- you'll be surprised how often they come in handy for solving costume-related problems.