OK, I'm tempted to pull the trigger on the glass press that you and @jdm suggest, but I feel confused about the dies.
May I ask where you got your dies? Will I be needing adapters as shown in the ad that @jdm linked to, and do you think those would actually fit? Perhaps those dies and the adaptors would work really well with this tool? Googling "M6-hole dies", "M6-hole glass press dies" and similar I'm afraid hasn't been very helpful...
The armoured glass I'm currently trying to fit a to Vostok Amphibian (Vintage Albatros Radio Room from the 80-ties) is approx. 31mm.
Sorry for going on about this!
I have found this on ebay. The same tool you are thinking of buying for a hell of lot less money. What I do not like is other stuff at his shop looks like rubbish
He means that rotates relative to the spindle. If you pay attention in your picture you see the upper die support being a bit tilted one side, that is because it's free to move, as it couldn't be otherwise. It's pointless to push sellers for much technical data, they are sellers not watchmakers.
Once again I suggest that you go for the other type, the price in the 1st link you included is robbery and the design is, after all, outdated.