This is an extension for the Westinghouse WFD100W dehydrator so you can fit spools of filament in it. Each extension is 70mm from shoulder to top and should allow for a full spool.
This should also work for similar models such as the HomCom FD704 available on eBay.
The part is modeled and oriented as it would be on the dehydrator so be sure to flip it upside-down before printing. It should print fine without supports. I recommend using rafts or brims since the part is very thin. As for infill, since the part is thin I printed it solid but it should work with fewer perimeters.