We've got three boxes that nest inside of each other. Metal frames with wood on top. They're painted with a sand-primer mix so that they have decent traction in the wet. They were built to fit in my dad's pickup truck so we just load up and go. We've also got two welded triangles that fit inside of the boxes, and an adjustable sidehop bar that collapses down.
I'm not at home so I can't get pictures, but I'll post some when I get back.