I have officially started making my control arms today, starting with the rear trailing arms.
I started by making a simple welding jig with some scrap metal.
Then I cut the OEM arms at the kink. I no longer need the kink as I have lowered the trailing arm pickup point similar to what the MCA Suspension "traction mod" does. Also this car will run much less droop travel than a road going car.
The jig keeps the original length but I have adjusted the rod end so that I can mostly lengthen the link as this is most likely what will be needed as I adjust camber.
Then I cut some tube to fill the gap and trimmed part of the OEM arm so the tube could slide in.
Here it is after welding, you can see I also boxed in the lower part for some extra strength.
Side detail
Then I quick clean up with the wire wheel and some cold gal primer.
These arms ended up being 230 grams heavier than the originals and cost about $50 AUD to make.