You could use a much heavier utility knife with tons of extra blades and a nice metal straight edge on a tough cutting pad or a plank of wood. The classic Stanley carpenter's knife has saved me many a time as it has a much beefier grip. You can then switch to #11 X-acto's as they are great for the small stuff where tons of pressure is not required. I've even used Medical scalpels, but they don't hold up.
Take your time, it's not unusual to spend a weekend just fighting through die-cut (or as we like to call it "die-crushed") wood., especially plywood sheets. On many kits the die-cutting is so bad that it has become the stuff of legend, on other newer kits, laser-cut sheets have become a Godsend. Above all be patient and go slow.
Best -- Guy
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