Hi, I've been using paper towels for my RTB because its super cheap, easy to clean and im rather lazy lol....that being said I was looking for an actual substrate....I was thinking maybe aspen but I was wondering what you guys think...I'd really like something cheap (kinda hard up for money seeing as I'm 16 and can't seem to get a job lol.....and also something easy to spot clean would be great too...what do you think??