So after these below,
This one on instructibles:
- Instructibles - Bike Innertube Wallet 'english retreads' and Crank also make stuff out of innertubes!
- Wallet from English Retreads
- Stuff from Crank
It so happens that an MTB tube (torus cut and opened out into a flat rectangular sheet) is just the right width for currency notes and two card holders!
Cut out three rectangles.
- Lowermost-and-largest one and second one (middle layer) hold the currency notes.
- The foremost-and-smallest one and the second (middle) one make two card holding pockets.
- I sewed them all up with a needle and black thread.