It's very simple to use items such as fruits and berries in a dehydrator because they hold up on the dehydrator's shelving without any help. Harder to manage are items that contain a lot more liquid, such as fruit leather, and making dried cookies, granola or other items that have a good deal of stickiness. Use wax paper or aluminum foil to offset these problems. You can also use parchment paper if you choose, but waxed paper gets the best results when it comes to especially sticky items.
Take off a clean tray from your dehydrator. Lay it on top of either a piece of aluminum foil or your wax paper.
Trace with the marker around the outside of the tray onto the wax paper or the aluminum foil.
Take your scissors and cut the aluminum foil just outside of the line if you are planning on using it to make fruit leather, as you will want to turn the aluminum foil up on the ends to make a shallow dish for your fruit leather mixture.
Cut just inside the line for a perfect fitting shape on your wax paper. If your trays have a center hole, then poke through the paper and fit it on top of the tray, working it open just enough to allow the hole to come through.
Place your items onto the tray and turn the dehydrator on. You will get the same results, but without all the mess sticking to your tray.