Back in the day, Larry, I taught a class on vacuum clamping. Had to create the syllabus from scratch. Was nothing out there 18 years ago. Dirt simple if you understand the concepts. Straight edge clamps clamp to a solid surface like your bench and your work piece is clamped by them. A vacuum clamp in this configuration is simply a 'plate' that have an area surrounded with closed cell tape. There is a hole within that area that is connected via an air hose to a vacuum pump. Fasten the plate to a solid surface (bench), lay your workpiece on top of the plate, making sure air cannot get into the vacuum area. Turn on the pump. Your work piece is securely held down and you can rout, sand, carve, etc. with no interference from surface clamps. You can easily make the plates from non-porous substrate to suit the occasion. I have a trunk full of them - somewhere.
Weakest dimension is sideways. If you plan to exert sideways force, use a physical reference pin to block it. This is the secret to CNC clamping as well. If you use a porous material like MDF, you will need to seal it. Vacuum pressure works because one side of the workpiece has a different air pressure exerted on it that the other. So the atmosphere pushes down to hold things down. Actually it works in any dimension. Interesting, fun stuff, learning how to use a vacuum pump in the shop. If there is a family gathering in your neck of the woods next summer, maybe I could do some demos on the technology. Hoping Jonathan will be well enough to go forward on that. Love to see his horses at work and play. Can't go to New York. No place for a single white woman traveling alone. Certainly not one quite as sprightly as she once was. Sorry, Allen. BTDT. Not again.