There are several types and brands of trailers worldwide. Some times people make them there own, and when good enough, they sell them. A nice example is the Karel van Vooren trailer, of which i had one my own.
I was a nice little trailer and most of it was polyester made, which made it quit light. A little disadvantage was/is that because it uses a torsion axle it needs a little weight in the trailer for preventing it bumping on the road while driving.
The trailer I have now is an aluminum made, so my guess is that it bounces a whole lot less than the other one I had.