seriously, rocks work great and even a caveman can use one ....
and don't go bitching about "it will destroy your edge, oh noesss!!"
sliding metal rails will destroy your edges as well....
or if you're a real rail-rat and have some beater skis, you could even use an angle-grinder ....
Belgium represent !
Once You drop in, it's all "Hakuna Matata" !
"The windows are vertical how am i going to poop on those?"-Killabees
"God isn't black, you fucking moron!"-Shibby
"I shit rainbows and sneeze glitter."-Arabian