Weight: Paper thickness is measured by weight. The higher number you see, in pounds, on the packaging label, the thicker your paper is. This doesn't mean you have to find the thickest paper you can—most card stocks are a great weight for invitations and can hold up to being mailed.
However, if a paper cutter sounds like a useful thing that has a place in your office, buy it! You don't need to shell out 贄 for a good one. This ษ trimmer has been a great little workhorse for me for about four years now, through invitations, photo albums, and many, many other late night print jobs.