The mock-up pieces are just there to suggest ideas for the upper arms profile. Real arms will have triangulation.
The curved tube idea is based on this cars suspension. The air foil "axle" is really the upper control arm.
My version would be more of a "dropped axle" and would be made of steel instead of cast aluminum.
This car has the same style suspension on both ends (IFS, IRS and FWD in 1935!)