In article ,
" says...
I am struggling with vacuum forming plastic in that my lab pump may be
the wrong type. May invest in a shop vac instead. I think they need to
be about 4 kwatts, much bigger than a home vac. Can anyone suggest
industrial brands that pump that hard? Even better can anyone name for
me their DIY vacuum forming vac cleaner please then I'll know what to
search for - UK availability essential

How about getting the blowers from a few scrap vacuum cleaners and
hooking them up in series with some rigid plastic pipe? Could be
problems with overheating if you run them for long though.
Or if your pump is capable of producing low enough pressure but not at
the volume required you could use a pressure vessel as a reservoir -
evacuate it first, then just open a valve when you need to suck.