Just finished this today. Took 15$ and a few hours to make. Super sturdy, was a little tricky to get the mounting symmetrical and balanced. 13' long, 20" high. Setting it up street style down tomorrow w/ some snow from the ice rink, so stoked.
they are industrial, so they wont be at home depot or anything like that. so start looking at large construction sites and road construction sites. I think their original length is 20ft, mine was already cut unfortunately. If you find one, make sure you have one or two strong guys w/ you....they are heavy as shit.