Hello. The basic "carrier" is a Curt aluminum cargo carrier, model# 18100; got it @ Home Depot for $97.00.
https://www.homedepot.com/p/CURT-500-lbs-Capacity-Bolt-Together-Aluminum-Cargo-Carrier-with-2-in-Folding-Shank-18100/205631477.
I ordered the aluminum angle from
http://www.onlinemetals.com/ I think I bought three seven foot lengths. {Sorry I can't remember}. I shall measure all the pieces I cut and send the dimensions to you. Can also send pics in detail if you wish. It's real simple to build seriously, as long as you can use a drill to drill the bolt holes. Mine is not "centered with the rack, so the trike is further behind the back of my car {Subaru Crosstrek}, so I can open the hatch back while the trike is in the rack. The rear of the trike doesn't stick out, the front does maybe about 8 inches out fro the side of the car. But it is a small narrow car. If you mounted it on a truck or bigger car I don't think it would stick outside the sides of the vehicle.
February 22