try the flat plastic stuff, its about 6-8 inches wide and any langth you want, it slides really well but it helps if you reinforce it a little bit, props on yours tho
^wanted it to be able to fit in the back of my car so i can bring it to school and sesh it during free periods, probably be building a bigger permantent one soon
im workin on a box right now i use some flower boxes my parents were gunna use but they dditn so it will be pretty good hopefulley im thinkin bout using lexan for the top sheet