Make printed slotted rear and top corners 90 degrees ,then the slotted top corner caps, then slotted lower rail base and ,slotted upper door frame ,to make a hard full legnth top cap. After getting the printed pieces, just add the 1/8" thick flat aluminum panels (bought locally) ,trim them using a/your paper template .So then slide the trimmed sheets into the slots maybe 1 1/2 to 2 " slot depth on the printed pieces .Use like 1/4 20 allen head screws every 6 " or so ,to make a Roxer topper . These parts would be so easy to ship.