Simple rings (with inside taper) to create temporary ventilated lids for our little friends.
4 top, 4 bottom layers, 2 perimeters.
The rings allow various materials to be used; samples shown include plastic window screen, waxed paper, cotton gauze (cheesecloth), and aluminum foil.
The nominal sizes are A = 1 3/8", B = 2 5/8", C = 3 1/8", and D = 4 1/8".
To ensure a snug fit with different materials a few layers of tape can be wrapped around the top threads of the container.
Rings can be re-scaled to fit whatever round containers you have on hand, or remix the parts as your needs dictate.