2x4s are cheap. Overbuild because why not. Even if it's just a pvc rail in your backyard it's nice when it holes up and doesn't get all wobbly or sag in the middle. Some cross bracing goes a long way. Also throwing some wide feet on it can be helpful to keep it from rocking or flipping if you're spinning on/off. You can go wide as fuck on the first foot because you'll be jumping over it.
Some scrap carpet can be nice to keep things sliding nice without too much snow.
If you can buy a cheap miter saw that's always a plus. Then just buy a bunch of 2x4s and pvc tubes and see what happens.
Some good threads in there and I think TC had a thread in the main forums about how to build a backyard rail. Not sure what it was called though.