Need a vacuum system for acrylic sheets

I have tried small vacuum pumps, with no success. I have even tried a
shop wet dry vac with no success. Has anyone used a venturi system
for large sheet work? I am using bullet catches through MDF (atually
melamine) with about an inch of vacuum space. Is there a better way.
I would be interested in purchasing a system if I could find one that
would work with Bob Campbell's gantry design (low to the ground).