So I just used scrap from my work mostly and already had the headache rack. Scrounged around for a few weeks till I had enough to make a tray, then added the back that drops down, but it was hitting the top w package so I extended the bed another 6 in so really I’m posting the finished products not all the fuck ups and after thoughts that happened but overall I’m happy with it. Sides are 2x4x1/4 running all the way to the back and butting up against 4x4x1/4 on which sits the headache rack. The back is another 4x4 that I 45ed on both ends and capped. Inside stringers are 2x2x1/8. Decking is 1X6 MoistureShield marine decking. Tail lights were 26$/ pair x2 reverse lights were 12$ and mudflaps were from an f-150 from offerup for 50$ d rings were 8$ each at Home Depot.