I use Hovabators , with vermic right in the bottom....the bottom has been replaced with a lerger , taller shipping box (styrofoam)....I use 2 to 3 inches of vermic....and each HovaBoator will hold from 4 to 6 clutches of eggs....I wish for 4 per incubator...it means more eggs and larger eggs....less duds also...(*I run 4 'bators at a time....as one is emptied it is refilled usually with new clutches...it beats all the eggs in one basket...and yes...I have killed a whole 'bator full once...)...
.....go to a store and walk around...you'll find something in every size....be prepared....
....good luck....
-----
........JY