A forum dedicated to DIY RV

While not travel trailers the Toyota RV forums and facebook page do quite a bit. one did a complete new frame with aluminum.

There is THIS!!

free radical wrote:
You could also try here
https://www.expeditionportal.com/forum/

There's some seriously out of the box builds over there. You can kill an entire weekend on that forum no problem! :B

There's at least one other member who has posted some "virtual" projects, you may be able to search. Winter is a great time for mental exercise, aka noodling!

aluminum trailer frame, how about carbon fiber? you can buy the fabric in rolls and epoxy in jugs and build your own. Could do the same for floor, wall, etc. might need some plywood molding for certain shapes? aerogel panels for insulation instead of old school foam. a lot less weight and better R value.

I wonder with the right molds, maybe a monolithic shell could be built, instead of regular walls, floor, ceiling, kind of like those bathtub type fiberglas trailers you see now and then.

some 'House Trucks' have slide outs
i have seen several youtube videos on that
these were manual NOT powered, big rollers under floor

Those are all good suggestions, but I am interested in some "out of the box" solutions.

Like aluminum frames (not just walls). Foam between the frames and glued to the subflooring (must be non-wood).

Square, aluminum tube, walls, the exterior must not contain any natural fibers (like Azdel).

Square, aluminum tube, roof joist bent in a arc. Roofing can not contain any wood fiber so ... Also the interior ceiling will have foam insulation.

How do you actually build a slide out ?

oh yes, Expo is a good one! And Sportsmobile has a home-built section in their forums, many of the same people. there's also cheaprvliving.com

You could also try here
https://www.expeditionportal.com/forum/

Skoolie.net may be another place to check out. Obviously there are some things that skoolies deal with that a homebuilt travel trailer would not (such as the drive train), but a good many of the systems and so forth are also similar.