We have some 20+ year old Curver boxes - not sure of the exact model. The EAN code suggests that they were called  “Curver Toy Box 29l” not sure if they are still produced and under which name.

They are nice and sturdy, but have one flaw: the handles are open holes. This means everything in it gets dusty.

This print is an insert to remedy that problem. The insert snaps into the handle hole from the inside.

Printing one with in Draft mode (0.3mm layer height) takes about an hour. I used PETG but PLA might work too.

Fusion and step files included.