Dump box from a utility trailer?
Back half of a Buick LeSabre?
I think you could get more useful response if you share the reasoning for metal. Do you need weather tight? Do you need structural stability? Do you need durability? Do you want it to be pretty?
My suspicion is that the size range you listed is large enough that pre-fab will take some creative searching. You might be better off working with an HVAC or sheet metal shop to make something fit what you need exactly.
As a side note, I’m pretty sure I remember reading that you aren’t supposed to smuggle people in refrigerators, they can get caught in there and drink all your beer.
I've seen a lot of 'DIY' teardrop trailer construction from various sheet materials, all very interesting constructions. None of it looks difficult. I think the cost of sheet metal to make it would be prohibitive from a DIY perspective. My own recent searches for 4x8 steel and aluminum sheeting is coming in around $10-12/sq'
That's a custom build size! I assume, Top opening, with struts to keep it open as you pull stuff out? Call Shorty @Aluminess, all they can say is not thanks. You may find a local builder who can build the frame and top, you sheet it, and secure it. Just my thoughts. DG
I happen to know for a fact that Adventure Trailer sells pre-made metal boxes for trailers.
I think it'd be rad if there was a prefabbed box that would make a great trailer. Chances are you're gonna have to pay to play to get what you want. I built a custom trailer, it was fun but I couldn't find anything on the market to really work that was already built. Best I could come up with was utility trailers for the power company and even they needed so much work to get them to where I wanted them... building from scratch was faster and cheaper.
If you want a less expensive option, look for an m416 or a canadian m101 trailer. Proven and often can be had inexpensively.
New Reproductions Complete Trailer Assembly Kit (with chassis)Original thickness steel assembly with fender wells. Great additional to your military or civilian vehicle. Comes painted in primer.Kit includes:MB Trailer Assembly with ChassisMB Trailer Eye LunetteMB Trailer Leg SupportMB Trailer...
You might pull something out of a barn, but by the time you fix all the rust and knock out the dents, you still generally still need (or want) to swap out the springs, axle, rewire it, etc. (all of which adds up). Try starting out with a solid base to build a trailer from.
Adrian Steel makes a line of steel boxes for service vans, so there might be a standard item in their catalog. When i needed a six-foot drawer for the back of my truck, I had it fabbed by and shipped from Ainley Kennels. I think they are in Iowa. Steel storage cabinets can be found close to your dimensions, but they are set up for vertical applications.