Swiffer Wet Jet Refill-mod

Print both parts without support.
You'll need a rubber gasket as well, though it might work without one.
I used a 32mm rubber O-ring (The actual ring itself is 3.46mm thick)
It came from a Scuba diving repair set. "Divers O-Ring Kit: AS568-214"

The threading is TIGHT, you'll need to spend 5-10 minutes screwing & unscrewing in order to wear them in.

I used hot melt glue to adhere the Base to the top of the swiffer container after I popped a big hole in it. Make sure to completely clean the top so the hot melt sticks. You'll need to go back and apply more glue once you notice a few pin hole leaks!