Some corrugated cardboard is too thick for a razor blade or craft knife to cut through. Trying to force any knife through thick cardboard can get dangerous and slips may result in serious injury. A rotary multi-tool with cutting blade attachment has the power to make a quick cut, even through thick cardboard appliance boxes. Take a few steps to protect yourself then power through cardboard to create any design you can imagine.
Mark the thick cardboard piece with a permanent marker guide line that is thick and easy to see.
Put on work gloves and protective eyewear to prevent a remaining staple or jagged edge from causing injury.
Plug in the rotary multi-tool and turn it on as you press the edge of the cutting blade into the beginning of the guide line.
Run the tool through the entire length of cardboard to complete your design.
Turn off the rotary multi-tool and use sandpaper to smooth any sharp edges created by your new cut. A vacuum is helpful to clean the cardboard dust that is made by a large cut through thick cardboard.
Laminated cardboard may have many sheets glued together and may require a cut on both sides if the cutting wheel of the rotary tool has too small of a diameter to get through in one cut.
Be aware of hand placement at all times and never hold the cardboard anywhere near the cutting guide line.