I couldn't locate my Dremel nor any NiChrome wire (which would have been cool). So I went with the coping saw. It did produce a slightly rough edge but nothing that would be an issue so I am not going to take the time to clean it up.
Here it is all assembled. The connecting piece is a short section of the female end of a 2" PVC pipe. The bottle fits in the female end and about an inch and a half of the normal diameter of the pipe fits well, though not snugly, in the hole of the 'Large Hopper Adapter' board.
Goggles will only be required after drinking a bunch of the beer this will help produce.