I have several fermenters going right now - all free from the local grocery store bakery dept. Learned the tip from this forum. . .Walmart, grocery, etc. ask if they have any empty icing or donut glaze buckets. The keep a few empties & give em away if you ask.
A 1/2" hole (use a spade bit) fits a standard grommet perfectly (LHBS or on-line for $.25 or so.) Some buckets have lid gaskets, some don't. . .doesn't matter, ferments your beer either way. If you use a freebie bucket without a gasket you won't see much (if any) activity in the air lock. . .doesn't matter, the airlock is just to ensure an active ferment doesn't blow the lid.
Any bakery or deli bucket will work except pickle buckets (you'll never get the pickle/vinegar smell out.) One "drawback" to icing/glaze buckets is they all seem to be 3.5 to 4.5 gallons. Perfect for 2.5 - 3 gallon batch (2.5 gallon = 1 case o' brew.) Works for me as I brew lots of half batches & tweak (recipe development.) But you can also brew a full batch & just use two buckets. . .so the size is not really a drawback afterall. . .it's a benefit! YMMV
PS: I currently have 6 of these freebie fermenters in my rookie bruha-hause. Life is good
PPS: When you score the freebie buckets
with lid gaskets don't turn those into fermenters. . .perfect storage bins to keep your bulk DME dry
Thank you homebrewtalk forum for all you've taught me!