A spare part i made for the bottom of the 25L KNÖCKLA trashcan from IKEA, as mine broke. The part is extremely sturdy if printed with 25% infill (grid or gyroid) and 4-5 walls. Print it in a durable material with a little give like PETG, ABS or ASA. It looks like it also might fit the 50L KNÖCKLA trashcan, but I do not know.