In the age of mp3s, most people have a lot of old CDs lying around. Instead of throwing them in the trash, though, you can put them to use in a way that's both eco-friendly and healthy. Thread the discs onto the ends of a thin metal rod and secure them in place with bolts to make a usable (and cool-looking) dumbbell. Tape up the middle of the rod to provide a comfortable grip, and you'll be all set for a workout.
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Good idea for my old CD's.
Better way to make sure you don't mess up the threads on the rod is to put the nut on before cutting, then if cutting messes up the threads you can just unscrew the nut and it will fix the threads on the way off.