The factory lid for the Spec V 5 gallon fish tank is kind of crappy.  It's awkward and a nuisance if you want to be able to mount a better aftermarket light, and it is a pain to simply feed your fish with this big slab of plastic in the way.

This replacement lid is much easier to live with.  It just covers the “living space” of the tank, so the filter section is readily accessible to add water.  There are generous slats for air movement, and it doesn't interfere with generic aftermarket lights.  But the best part is the liftable hatch that lets you feed your fish with basically zero effort.

Print the two halves as provided.  I did one of each, but you can do two hatch halves or two solid halves if you prefer.  A transparent or translucent material is ideal.  For the hatch hinge, simply slide a piece of filament into the hole, all the way through to the end.