the pro’s toolkit: If you’re willing to invest in a more specialized cutting tool, you’ll be able to easily make professional-quality mats that have nice, beveled (angled) edges on the windows. Handheld mat cutters generally run about $20 or so, and can be found at art and craft stores. If you want to get a little fancier, a mat cutting system consists of a straight edge with a hooked lip that holds the mat cutter in place while you’re making your cuts. I have a Logan Compact Mat Cutter that’s served me very well in the five years or so that I’ve owned it – at $80-$100 or so, it’s not exactly cheap (although it’s definitely one of the more affordable professional-type mat cutting systems available – you can find ones that run upwards of $300), but if you’re planning on cutting mats often, as I do, it makes the job super-easy.

mat cutter for cutting beveled edges
mat cutter for straight edges or exacto/utility knife
straight edge, preferably one made to go with the mat cutter, in such a way that the mat cutter can hook onto the straight edge to help guide it along
yardstick with t-square end
extra mat board on which to make your cuts
pencil

The answer’s simple: cheap mat board isn’t acid-free, and if you’re concerned at all with protecting your artwork for years to come, you’ll want to go with the museum-quality/archival mat-board. If, on the other hand, you’re framing something that’s not intended to stay in your permanent collection of wall-art – that picture you cut out from last year’s calendar, for instance – then low-end mat board will serve you just dandy. And even non-acid-free mat board is generally much better for your artwork than cardboard.