[Karren H]

I managed to get a prototype kind of working. Using the top portion of 2-liter soda bottles for the domes, and the sprinkler tube to suck the air out to control the pressure. Using electrical/duck tape to secure the tube and as cushioning around the bottom of the cut out portion (2 layers of tape, but is a bit thin and the edge still digs into the skin a bit). The issue I'm having right now is that is isn't fully airtight, where the tube and the top of the bottle is basically layers of tape, and the bottom isn't entirely airtight even when sucking. Would a couple extra layers of tape fix that? Any recommendations to make sure the top portion is airtight?

I'm not very handy, so sorry in advance if I'm missing something obvious.

Soda bottles were designed to withstand internal pressure so when cut, they provide very little structure to support negative internal pressure (or positive external pressure).   And no amount of tape or hot glue will make anything air tight, IMHO.   I use objects that are thick walled like pvc pipe with threaded barb adapters to attach automotive grade vacuum tubing.   Then I use tees and valves from the fish supply store.   Any pump will provide couple negative psis, even your mouth.   I use an automotive brake bleeder pump to get up to the 10 to 12 pis range and my systems are so tight that they will stay pressurized for 3 or 4 hours without re-pumping.  Typically at that pressure I can only take it for a couple hours....  all night at about 5 psi.