John,
Too answer your question it is a metal trailer.
I used a hacksaw and cut the tongue off first, then cut all the cross members in the middle. I used brass tubing, just large enough to slide over the cross members. Then I slid a piece of rectangle plastic in the round tube to make it tight. It would have stayed together without any glue, but I put CA glue in each end to secure it in place. I filed a flat spot for the three tongue brackets and glued them with CA glue. Then painted it black.
I live in a very small town but we have a combination grocery, hardware store within five miles. They have a display case, with many sizes of aluminum and brass tubing and also flat sheets.
Bob