You can buy all the stuff you need to fabricate a set of side rails for your trailer at Pacific Trailer (https://www.pacifictrailers.com). As others have mentioned, you can find the indoor/outdoor carpet at the hardware store. I have used the pressure treated wood for the side rails on the last go round...honestly not sure if that is an advantage or not...one thing with pressure treated, no one will cut it for you (not that difficult...just reeks...make sure you dry it out). Also remember to put anti-seize or marine grease on your bolts..or they may "mysteriously" weld themselves together...lol. Good luck with the project, I have been doing the solo launch/retrieve thing since the 80's, just drive the boat on/off, once you get the hang of it, it's pretty easy, side rails do make it alot easier, especially if you don't use the dock, like me.