The fuel return line is made of 3/8" aluminum tubing. I opted to use a stainless steel fitting for the firewall bulkhead. This bulkhead bracket was made from 1/2" Poplar. The goal here is to encase the entire return line and bulkhead fitting in flox so that no movement would be allowed when adding the neccessay fittings to the bulkhead. I then added 1 ply Bid over the wet flox and peel plied. Later the poplar bracket will be contoured for a better turtle deck to spar stransition.