Found someone on reddit that tested a bending jig from thingiverse
I think I'm gonna try this instead of the unistrut method
CETME and HK flat bending jig by Tankoj
This is a printable bending jig for CETME and G3 receiver flats to both bend the flat evenly, and keep it properly shaped. It should work on all HK style flats, but I don't have any others on hand to test. The "Mandrel Filler" pieces should be installed once the flat is most of the way there...
www.thingiverse.com
I think I'm gonna try this instead of the unistrut method