I got the idea from looking at cardboard and wantng a duel disk. I figured, waht the heck, and from there I just put the pieces together.
My computer has no way to upload pictures so I had to make everything on paint for examples.You have been warned!!!!!!!!!!!
Step 1: Gather materials
~ Cardboard (And lots of it!)
~ Small calculator
~ String or Velcro (To fix this to your arm)