I think you could somehow fashion them into birdfeeders. Our bird feeder has sort of a mesh bottom .

My dehydrator trays are round and have a hole in the middle. Could be used as the middle of a flower or could be put on a pipe and fashioned to rotate in the wind.

It might kind of depend on what kind of dehydrator trays they are. Some are big square "shelves" kind, others are round with a hole in the middle.. there is some differences in sizes too.

You could string them together in levels like hanging baskets to stow stuff on. Or hang bundles of herbs off them. Or make it into a windchime, or bird feeder, or a rain chain. You could fill the gaps with liquid glass to make crazy stained glass pieces. Or weave in threads and make dreamcatcher sort of things. Or string with beads and use LED lights to make an interesting sort of chandelier kind of light.