I built mine form some old steel lifts we got at work, the steel was too thin to weld so I had to pop rivet it all together, its 26" wide, 11" high and about 72" long (so I used one sheet of white 1/4" pvc puckboard).
The hitch is welded, its made of 2x2" angle iron, the part where it hitches onto the snowmobile slides back and forth and has springs as bumpers. I mounted the hitch low on the toboggan, right where the curve in the front starts, this way when I go over trees it will lift the toboggan over and not hit head on, I also find that mounting the hitch low pulls the back end of the snowmobile down and gives more traction.
I used it without runners the first time, but when I was on hard pack or planing up it would whip from side to side, so I put some poly runners on, it was just materal I found in my father inlaws hanger.
I use this toboggan to ice fish, go to our outpost cabin and haul firewood, its no problem to stop in powder with a full load of wood and start again.
