Some cutting jobs don't suit a folding pocket knife. Cutting paper, carpet or anything in a flat sheet is best done with a Utility knife. Often called a Stanley Knife (after the brand, a bit like Hoover etc) or a carpet knife - Utility Knives usually have a retractable, replaceable blade.
I did have an old Stanley Knife in the workshop which I'd used for years. Then one Christmas my then 8 yr old son bought me a Hultafors Utility Knife as a present. (He'd gone into a local Independent hardware shop with Louise and chosen it himself as something I would like. He was absolutely spot on. We've always encouraged him to choose gifts for other people and buy them himself. Only issue with this story was that he was gutted that he wasn't allowed to hand the money over .... falling foul of the age restrictions on buying knives ... he most definitely wasn't over 18!)
This knife is a solid zinc metal construction. Great grip and reassuringly heavy, which I think helps with the cutting action.
Changing blades is really easy with the large turning wheel. You also get 10 spade blades within the body of the knife.