so one of my other hobbies is woodworking and i was watching a video online about making a vacuum bag to clamp veneers down. what the guy used as a bulkhead i thought was genius. he took a screw-on plug for a sink and drilled a hole in it. this is one of those plugs for stopping up an extra hole from a soap dispensor or a spray head. i am not sure of the diameter of these because i only saw it online. i was looking for 1/2" bulkheads to try a recirc mod on my bak pak skimmer and i think these may work. i do know you can thread fittings onto the end of these plugs because that is what the guy did. these plugs come with a gasket. the guy was making the bags out of shower mats (the rubber you line a shower with). this same material could be used to make custom gaskets. let me know what you guys think or if you have ever heard of it before.