Not wood, it's really soft and super easy to to catch an edge in. My backyard jib that I have is made with pvc pipes and it works really well and is super cheap. HDPE (high density polyurethene) works amazingly but is expensive and a sheeting. Puckboard (hockey rink boards) works good as well so go to your local rink and see if they have some old stuff. The downside to puckboard is it can get sun ripples. like my mountains boxes did.
metal... get a friend who knows how to weld, its not to hard, rent a welder and a grinder and buy some steel, total you about 200$ but you can make whatever the hell you want. im rockin a 22ft flat-down-flat-down in my backyard:P
I set my drop in on saturday and have only got like 2 inches of snow. I bought astro turfand put it on my ramp then put the little bit of snow i have on it and it works really well. We are supposed to get 10cm today so it will be even better.