Thin and very flimsy plastic
Test thing about this tray is the integrated clips system so no lost clips. The top doesn't fit easily onto the bottom, there's a gap at the front between the two part parts.
Door attachment clips are poor, door comes off too easily and may remove this if cat doesn't like it, as the old tray had lid but no door.
The old tray has been in use for 20+ years and been used by two previous cats, I thought it time for a new tray for the new cat. Not sure this was a good idea after all.