Another old fashioned straight-edge and matte guy here.
You need a table anyway. So build up a 4x8 table with Home Depot technology. Cover it with a 4 x 8 cutting matte
Buy a couple of foam-bottomed, stainless-edged staight edges
in sizes you like. I've got the 64" and 100" models, don't feel the need for anything else. The big ones have some weight which helps clamp down the art. But when you get them spend a couple minutes de-burring the ends with a file. The straight edges have foam on the bottom, which keeps them in place and allows me to fearlessly place them over the image areas of fine art papers and canvas. And I like the "safety" straight edges not so much because they're safe, but because that vertical thingy is a terrific aid to keeping your utility knife vertical, one kinda registers one's little pinky of one's cutting hand against it as one makes the cut.
Oh yeah, forget those stupid Xacto knives. Use a man-sized Utility Knife
. Make sure you get a model with a quick-change blade release, fiddling with those old-fashioned screws is a pain. And the only utility knife blades worth a hoot are Stanley #1992 Heavy Duty Utility Blades. All those other, fancy, hi-tech blades you see on the rack are frauds.
The matte I indicated has no markings. If you must, get one with markings, but don't count on them for precision work. That matte is also a great surface for joining polystryene frames, which is the Future of Framing. framah may disagree.