(First off sorry for posting completely off topic for this forum!) just had no where to go for help I'm looking to make a seat on a roller (the closest thing i could relate it to is a rowing machine on a similar metal strip) I'm not great with the construction (I've created a quick design here) http://img6.imageshack.us/img6/2888/mock... What materials would i need for this? I would prefer to use plastic, but are there any better / cheaper alternatives as im not convinced the rollers will run smoothly down the plastic!