BulkHead Fittings
 

Where can I get bulkhead fittings 1", 3/4", 1/2" without having to pay a
fortune. (mail order)
These are fittings with a nut on both sides so you can attach it to the
bottom of a vessel or container,
eg: used to make a biological filter out of a plastic barrel, so you can
attach a hose to a vessel etc...
My local hardware wants 28$ for a 3/4" fitting.