The cable used is LAPP ÖLFLEX Classic 400P 3G2.5 PUR.
This is the same cable specification used by Foil Drive, selected for its flexibility, abrasion resistance, and suitability for high-current mobile applications.
The 3-pin connector was designed by another forum member, JonathanC, who has the 3D print files available. If you message him directly, he should be able to share the files and offer guidance on the build.
If you need any additional information on parts selection, wiring, or VESC programming, just ask — I’m happy to help.