You're going to make your own power supply cables? That sounds awesome. I have no advice for that. Have fun.

As far as I know, no one does that because that sounds like a good way to fry some components and/or cause a fire. When most people say "custom cables" they mean just buy a kit from cablemod.com or something.

If you don’t want to have serious trouble, buy a crimping tool meant for the specific crimp you are planning to use. Crimp tools tend to cost $100-200, so budget for that.

I once considered this. Found this