Just to see if I could do it using my new patterns, I made a pair of webbing strap sandals. Before that I tried to make a pair of arch strap sandals but something went wrong along the way and the left one came out so tight I couldn't quite put it on. I may see if I can take them apart someday and finish them, but I'm not sure if it's worth it. But the webbing sandals worked.
I made them out of dog leashes from the dollar store, mouse pads and old flip-flops. The dog leashes were only $1.50 each and came with the buckles I needed. It is impossible to find buckles like that at craft or other store. They only seem to sell giant ones for making laptop computer cases or whatever.
Basically, the only part of my sandal patterns I used was the threading pattern for the straps. Otherwise, the instructions expect you to use leather and to stitch the top sole to the mid sole and use little nails for strengthening the stress points. I just threaded the webbing through the mouse pad then glued it to flip-flop soles, taking care to leave spaces for the continuous strapping to remain adjustable.
I have no idea if they will hold up or fall apart. I can always re-do the top sole and re-glue it to the flip-flop, perhaps use better materials and do the stitching and everything that is in the instructions. I just wanted to see if I could do it.
They work, so I'm happy I gave new life to an old pair of flip-flops. These were the flip-flops I bought in Cabazon when I was hiking the PCT in 2008. I wore one of them for 15 miles one day because my blisters were so bad. I hate flip-flops and have never worn them again. These ugly dog-leash sandals will give them some sort of new life. Unfortunately, mouse pads are really heavy, so their new life won't include becoming camp shoes for backpacking.
Update: These fell apart after wearing them for about 3 miles. Also, my foot falls off the back. Why does this always happen with my attempts to make sandals. Any kind of sandal. This all started with me wanting to make a pair of huarache running sandals like Barefoot Ted, but even those had my feet falling off the back.