The Bar Towel

I'd like to stopper 6 litre better bottles with 2 inlets, one for an airlock and the other for a thermowell.

Options that I've seen so far are:
Drilling a 2nd hole in a No. 10 drilled rubber stopper (problem: drilling hole through rubber is a pain in the ass)
(Orange) Universal carboy cap (problem: apparently it's not a great fit on the better bottles)

Anyone crossed this bridge already?

Is the orange carboy cap too large for the better bottle? I used one on a 6 Gallon glass carboy that wasn't airtight and put one of those thick elastics you get around brocolli at the supermarket and it helped seal it up.

phirleh wrote:Is the orange carboy cap too large for the better bottle? I used one on a 6 Gallon glass carboy that wasn't airtight and put one of those thick elastics you get around brocolli at the supermarket and it helped seal it up.

I've read that it is a bit too large for the BB. I've also read of the rubber band solution, which I'm willing to give a shot. I just typically like to see whether there is a purpose-built, reasonably priced solution first, with retrofitting as plan B.