Here's a trick from the off-road world. I made these struts to support the fiberglass bedsides on my Tacoma. 1. Flatten some tube in a vice, can be square or round. 2. Clean up the ends on a sander. 3. Drill mounting holes in the flattened ends. 4. Krylon! 5. Bolt it up.
hell i could use those on the metal sides of my truck thanks guy! i was wondering how i was going to stop those things from flapping..
I made some fender braces out of tubing like these for my 39 Pontiac coupe in the early 90's and they are still holding up. No flexing at all.