Anyone who likes DIY knows that material can make all the difference. This rating system is an attempt to give would-be gear mad scientists a heads up on how easy or difficult it will be to find the materials needed for the projects listed. Of course, this is subject to locale.
1: COMMON HOUSEHOLD ITEMS. You probably have the necessary materials laying around your house somewhere but you might have to dig through the junk drawer a while to find them.
2: EASY SCAVANGER HUNT. You may or may not have them at home but a quick jaunt to the hardware store or auto-supply store will fix this. These are readily-available materials that might even be found at 7-11.
3: A LITTLE MORE INVESTIGATION. You might have to order these materials off the internet or take a quick trip to a specialty store (like a craft store, sewing shop, auto-parts store, etc.) but they shouldn't be too hard to find.
4: NOW WE'RE GETTING SERIOUS! These materials can only be found at highly-specialized sources. You'll find yourself sourcing materials from the Internet or industries that have nothing to do with backpacking. And, they'll think you're crazy.
5: UNLESS YOU HAVE CONNECTIONS AT NASA, FORGET IT! These are materials that the hoi polloi are pretty much restricted from and trying to obtain them may cause an international incident. Good luck!