CardSharp2 Credit Card Folding Knife

The CardSharp2 spends most of its life pretending to be a credit card. It measures 85.6 by 54 millimeters, it is 2.2 millimeters thick and it weighs 13 grams, so it slides into a wallet slot next to your real cards. Three folds turn the flat plastic into a small utility knife with a 2.6-inch blade, a bit like origami that ends with something sharp.

The clever parts are the safety details. The sheath is built in, so it can’t wander off and leave a bare blade in a bag. A small hilt appears when the knife is open to keep your fingers off the edge, and a snap lock holds the blade steady once it’s unfolded. The folding mechanism is made to shrug off water and rust.

It makes a fun stocking stuffer for the person who opens a lot of boxes, or for anyone who likes a gadget that gets a “wait, show me that again” from friends.

The catch: the body is plastic and the blade is a thin, utility-style blade, so treat it as a handy cutter for cartons, string and pencils, not a knife for heavy work. It’s steel, so it will set off a metal detector. Leave it at home on travel days.