I've been making my own power cables, connecting battery to contactor, contactor to starter, main fuse block (rear firewall) to the front fuse block (instrument panel), et al. I started with the Bob Nuckolls recommendation for fat wires - make cable ends from copper pipe. The result was great in carrying current, but way to difficult to get good looking ends with smooth bolt holes. I bought an assortment lug ends and a hydraulic crimper. The result has been much better. One of the lug ends had too small a hole, so I had to replace it. That was a chance to cut into the lug and check how my squeezing was doing. OK! See the two photos below. The first one shows the cable just outside the lug. You can see the individual wires of the 4AWG cable. The second photo shows a cross cut in the center of the lug. Under compression the wires merge into a solid mass, and there is no space between the copper and the tinned copper wall of the lug. I didn't get that solid metal look all the way across the cable, but there is still one heck of a low resistance connection. I don't know that all the cable ends are this good, but this one looks acceptable. The spend was on a hydraulic crimper (Klutch brand from Northern Tool) and an assortment of lug ends (Amazon, their larger assortment). Make sure to get copper, tinned, with a tang end opening so you can add solder if you want to.