Very happy :)
Been meaning to build this for a while but took ages to find a big cylinder and a switch.
I was going off JoeWoodworker's plans for a bit but he is overly complex, 110V, using a MAC valve to bleed pressure on the pump side as his oil-less diaphragm pumps (that cost 3x more....) won't start up against fullvac. All too hard. I like mine better as its simpler and uses any old cheap eBay pump at $100.
What was putting me off was the only really reliable mechanical diaphragm switch is the SMC ones - $300. Advantage is no relay required, simple, bulletproof, all industries use them as a standard. Then I saw one new, no box, from a closing down sale -at $80.
Then the elusive cylinder showed up on Gumtree. Nice
big 60kg refrigerant cyclinder as a reservoir so leak-down takes ages -and it has the same fittings as vac pumps cos its all fridgie gear

So I just had to.
Result....

Added a couple of taps so can do two jobs at once, nice.