I've got aventura cages myself and although I've looked at replacement trays in the past, I've found them more expensive than the cage itself. You could make your own out of wood, or as I'm doing thick perspex with adhesive tiles covering so they can't see through, but I'm reusing parts of another cage to extend levels so they have more space.
Sorry I can't be of more help.
Last Edit: Jul 3, 2022 16:04:22 GMT by savvy: missed a bit!
I once made extra trays for my Explorer by using a piece of perspex, then applying 10 X 1.5cm aluminium L profile using both glue and small nuts/bolts.
Being dragged through life on Bernard the Bike, with Squidgygoo (RIP), Spidergoo, Scaredygoo (RIP), Sillygoo, Sausagegoo, Smashygoo (aka Spud), Snoozygoo, Sneakygoo, Pootle (RIP), Perkin (RIP), Fidget (RIP) and Twitch (RIP) the pillions.........