Sorry, I missed these comments!
This was the first jig I made and the first flask I engraved, so my approach was a bit half-assed. There are much easier ways of doing this!
I only had 1/8" MDF on hand, so I made my jig out of that, but doubled everything up to make it 1/4" thick. The base of the jig has .75" legs supporting it.
The top is two sheets, with the flask cradle cut out of the top only. The T shape is to accomodate the open lid of the flask (in either direction). The 1/8" lip is enough of a frame to hold the flask in place. (I have no idea why there are extra pegholes in the middle, but I don’t think it was intended.)
I remove the crumb tray, and place the flask in the cradle. Because it’s convex, it doesn’t rock or move around. Note that the cap is off: I was told that the flask can build up pressure if it’s sealed and heated. I used 500/100 @ 450lpi, but there’s room for improvement.
In the future, I’ll use 1/4" MDF, I’ll make cradles for multiple flasks, and I’ll make the jig design and the flask design in the same document so I don’t have to worry about positioning it manually. (I hate monkeying with the camera alignment.)