I have ones very similar to these & absolutely love them. Initially I didn't care for the screen in the bottom, but if I take my fine trim after it's dry & dry sift it over the screen, I get a considerable amount of kief! It's quite comfortable on my wrists to trim with, far better than no tray. I wouldn't want to trim without it now, to be completely honest.
This is the trays I'm using, got it on Amazon. I've got a pair so my wife or a friend can help & have more comfortable wrists as well. The only thing I can think of to improve it would be padding where the wrists go.
Edit: more info