DIY method : If you have spare earbud caps around (I've heard skullcandy work, maybe also another type of earbud gel/cap) try wrapping your 14mm male joint with that to make a seal, then put your glass tube through the earpiece for airtight seal. The next diy option I would try would be to find the ID/OD of the mflb official WPA tubing, get that, then get a cork that will fit snug in your 14mm male (or scrape one down), and drill a hole through the center for your tube. (You're pretty well making a smaller version of
this that will fit inside your joint)
GonG method: buy a
WPA from mflb and a 14-14 adapter from somewhere like
this (buy a couple b/c cheap + low QC)
EDIT2: Didn't realize you already had a WPA. While waiting for the adapter from china to come in id probably get a roughly 14mm ID vapor safe tubing (which type this is escapes me, but that link should help a bit) or slightly smaller locally, and make an airtight [or close enuff until the gong comes] seal end to end from one 14mm joint to the other.
Which 2? Some interest in their larger tree stump bubb and their smaller one, but both seem like they have very basic function (willing to pay a little extra for the QC + american glass blown [can't be sure if they use chinese glass or american] though) A watertest of the ones you have would be much appreciated as their sale is ending soon!
edit: blown in washingston vs washingston sourced US glass are two very different things. playing devils advocate here sorry.