you can use astro-turf that is doused with water and soap, it works real well, but it takes a long time to build cuz u need a wood base 4 the inrun and 4 a small landing, we made one and did a few jibs last summer. it works nearly as good as snow, its just that u cant hold ur edge. you can also use foam matresses but they rip and you have to get them really soapy and wet before they slide.