It can be used, well it used to be able to be used. It broke after the second test. I need thicker plastic, which I knew beforehand but I still went through with the test since the lid was my biggest concern. Rubber mat will be purchased along with some heavy industrial plastic sheeting and then it should be good to go.
Money well spent. Below follows some bland images on the "details" of this beauty. Somehow this gives me the impression of "In mother Russia... ". Sort of a 40K-ork-contraption.
Here is the second run's break. It is an old pipe that I never bothered to remove completely. The inside of this fantastic machine is an old washing machine drum with plenty of space. Problems to get it completely airtight with silicone rubber made me just cover it in plastic and voila, it worked.
The intention is to attach a vault here - unless it turns out I'll never get the darn thing totally air-tight, in which case I stay away from that particular expense and just let the vacuum cleaner run the 6-7 minutes it takes to degass silicone.