Hi Paul, great idea to start this thread. I will be first to post my tip.
I pondered for a while on the best way to fix on the Lexan end covers to the Cougar controller kit. Finally came up with the solution of bending the ends of the Lexan so I could screw it to the sides of the cover. See attached pictures. I also used some instant gasket to seal the enclosure from moisture. On the end that has the B+ and B- bars I only used 3 screws, as the fourth one was going to be very close to the capacitors. To bend the Lexan was very easy for me, I let someone else do that!
The local high school did that little job with their plastic bender.
Greg