Battery Mounting Plates, 3D Files:
Skateboard Hub Motor and Speed Controller
http://s.click.aliexpress.com/e/mDFXgwcs – These are the exact ones I bought (affiliate link):
Skateboard mounting hardware.
Dual Core Power Wire
Little plastic plug that was hard to find:
https://nz.rs-online.com/web/p/pcb-connector-housings/8201472/?sra=pstk – This is where I got mine from, but use the page to help with finding something local.