AWESOME!!!! Thanks for the nice project pics. The carbon tape is brilliant...
The strongest glass reinforced epoxy laminate sheet is circuit boards... They have 7-10 layers and they are cured in an oven.
You can make a battery box for free from circuit board, using your technique! You'd have to print it in silver at the edges and it has silver solder flecks on it.
Collect motherboards from around the place, Personally I go for raids at the recycle center sometimes because it's fun, I get free bike batteries, free motors, fans... very many things
Take an axe or a chisel and scrape the capacitors and ceramics and chips away from the FR4 fiberglass board. You get free USB fem connectors for your onboard ebike charger too.
It would be easy to then seam the boards together using your tape/ prepreg. I improvised a side board for my battery box, it took 5 minutes to chisel the PCI sound card:
https://youtu.be/iVQB0cwwPoM?t=40
The chisel needs sharpening after every board, that's why an axe is perhaps better... Instead of Yellow, you have Green and Blue blank motherboards with silver in it