Re- attaching pizza tray.
If you buy a proper tray for your feeder then they come with a threaded thumbscrew to attach them to the underneath of your feeder. I guess Kate has used one of these? I removed my trays as the small drainage holes soon become bunged up with seed husks/bird droppings etc and mould quickly forms, unless you constantly clean them. I did drill larger holes in some of them, but they still go mouldy.
Heres a few photos of mine, different brands of feeders come with differest thumb screws..