Jet Tub Plug Set

My in-laws have a jet tub and only use the jets about once a year so they were looking for a way to plug the various jets and intakes so that when the tub gets used, water doesn't end up in the pipes to sit there and stagnate and get mouldy. Unfortunately, they couldn't remember the name of the manufacturer (the tub is about 30 years old), and using something like rubber stoppers was out of the question.

I was playing with Fusion 360 and had just figured out how to make a thread so I thought I'd see if I could make screw-in replacement plugs for the tub. To my amazement, they actually worked.

I don't know if these plugs are some kind of industry standard size or thread or whatever, so I thought I'd post them just in case someone else could use them.

UPDATE: If you'd like a set (or just one or two plugs), send me a DM and we'll figure something out!

UPDATE #2 (November 2025): Unfortunately, I'm no longer shipping plugs to the USA (Canada and other destinations are still OK). If you'