I need help building a ski box for my backyard terrrain park!!?

HDPE is going to work but it's expensive like $80 for a 4 by 4 piece. I'm not sure what they use in the terrain parks but i know it's extremely expensive because it doesn't ware down. They also but metal on each side so your edges don't dig in and ruin the sheet. I know this crappy hill near my house that build there boxes for there terrain parks with HDPE. So just go with that it will work.