Step 1: What you need
1m of 50mm nylon webbing.
1.5m of 40mm nylon webbing.
(quite easy to adapt to different widths of webbing, but that's what I happened to have around)
Thick black thread, synthetic if possible.
2 x toe clip straps, such as these from Zefal
2 x 4.5mm x 200mm cable ties.
The attached layout file, printed out if possible: