Maybe this framing problem has a simple solution:

I have a lot of 32”x40” (4-ply) mat board, but my mat cutter accepts sides no wider than 28.5.”

This means I have to rely on something else for my first (down-sizing) cut. Problem is, I often need this initial cut to be clean & perfectly straight. To get the job done, I’ve been relying on a metal yardstick & box-cutter (w/ a sharp blade), but even when I’m super-careful, sometimes this arrangement just, well, “doesn’t cut it.” It’s not the blade that fails so much; it’s the occasional instability of the yardstick.

I’m considering a better straightedge, and I found one possible solution (below). It’s heavy and stable, it has a rubber base, and I like that safety handle. Looks great! But for such a very simple job, it does seem quite expensive. And since I’m not a professional framer, my cuts are occasional at most. But I do like my cuts to be faultless.

Makes me curious if there’s a less-expensive option (or technique) that’s as effective.

How would you do it?