Cereal Bag Liners! Take a cereal bag liner and rip open the seams and get your dehydrator rack or the plastic liner that came with it for a pattern.
Then take a marker like a sharpie and trace the pattern onto the liner. Cut it out; make sure you cut off the ink of the marker.
Then lay the liner on your dehydrator rack and fill with food. I have used this twice for making very yummy granola cereal (tomorrow's post is the recipe; don't fret!) and they have worked well. They are obviously flimsier than the other and will curl up, so you just have to uncurl the curls to put the cereal on the top. I have yet to make fruit roll ups, so I am unsure if they would work for that, but they work for this and you just wipe them clean in the dish water and hang them over other dishes to dry and reuse.