I have taken plastic screen door screen and cut it to fit several shelves of my dryer. When drying ground meat the screens keep the meat from dropping through. The screens lift off for easy washing with other dishes and last for years.
To get small crumbly pieces off the dryer without dropping any pieces put the hole dryer shelf in a plastic garbage bag then turn it over and tap it.  After empting several shelves this way the dried food can be pored out of the bag with no mess.