[Edit: Uploaded the wrong body and valve. (They worked, but the 8mm hole was a little too big. Not enough sealing surface. So I reduced the hole to 6mm.)
The correct files are Body good.stl and Valve good.stl.
The hundreds of instant "downloads" are no doubt fake, but there was time for someone to grab the old files. If so I apologize.]

This valve can be mounted onto any bottle cap, assuming you can poke near a 5/8 inch (16mm) hole through said cap. 5-minute epoxy fastens it. Then the bottle becomes a sep funnel.
I used a 20oz water bottle. Nice tight, waterproof cap design. Easy to drill the hole.
Water bottle is very thin plastic, but it's transparent and disposable.
I had a piece of 5/8 conduit, and made a bottle-holder that slips over it. The bottle is plenty stable when the tubing is mounted vertically in a vise. Or use your lab stand.

Orient the prints so there is no support in the hole surface where the valve turns. The design is zero-clearance. I printed a few. After cleaning and UV curing, the fit is perfectly snug. Just work it back and forth, and ease it in there.
(Get an ultrasonic cleaner. They remove every tiny bit of uncured resin, using soapy water.)

The nut on the end isn't really required. I do love this resin printer's accuracy. Always amazes me how much detail is possible, like with threaded parts. I used 0.1mm layers here, but doubt it matters much.

You may want to grease the valve. I have no idea what chemical incompatibilities might exist. The other day I discovered that liquid resin literally dissolves ABS filament after a few days of contact. So testing might be wise.

NovaMaker Elfin2, standard resin, about 400 layers, 2 hours... 6.5 sec exposure time? I had no idea it was set that long. 5 sec or less should be plenty.

Print the bottle holder with filament, but this valve needs a resin printer.

elfin2

Doesn't Matter

Doesn't Matter