Here are the materials you will need: cardboard, bike tubing, scissors, a pen, and duct tape.
Step 1: Acquire Used Tubes or Tires
I rode my bike over to the local bike shop, and they let me look thru their dumpster. Select some dry tubes.
Step 2: Make a Cardboard Sole
Using cardboard, trace around your foot, and cut out. Put a dot between your big toe, and second toe, if you want the flip-flop style of sandal at the top of the foot.
Step 3: Cut Your Straps
Cut strips from a bike tube. Thinner strips are nice if you are going for a criss cross look. I cut strips that were the full length of the tube.
Step 4: Lace It Up!
Punch 2 holes in the cardboard, between your toes, and thread the tubing thru the holes, so that both sides come out the top, and you have a loop thru the bottom side. Put on your sandal, and punch holes in the sides, where you want the laces to support your foot. Thread the tubing thru, and adjust as needed. When you have a fit you like, reinforce the cardboard and tubing with a little duct tape. Enjoy!!!