What are easy ways to use a corny for a fermenter i.e. how do I stick a fermentation lock on the thing? I’m planning on using the corny for dispensing beer in the future.
Easy. Attach a blowoff to the gas in tube.
In the corny lid take the vent out place a bung with your bubbler or blow off tube in it. Some people also take gas fitting off and do the same. While your at it take 1 inch off the dip tube then when you want to transfer (replace gas fitting or vent) hook up co2 with low pressure and transfer to another keg.
This. You may be concerned it will clog, but remember the keg is rated to >100psi. The clog will blow through the tube long before the keg seals fail.