Here's my home made Kafer Cup brace.
The tubes are hollow T6 aluminum, except for the ends, which were solid T6 'till I turned them down to the tubing's inner diameter, and drilled and tapped them for the fork ends on a lathe. All the chassis connections, the fork ends, and the shock tower pieces are steel.
The front brace was made the same way, but it's all aluminum, 'cept the fork ends.