Sharpening your rotary cutter on the cheap

I was looking for a rotary blade sharpener online as I go through a blade a week (despite not cutting that much- I think I'm pressing too hard or cutting too many layers). However I came across a cheap way of doing it...Take an arms length of foil and fold it up several times.Roll your rotary cutter over it over and over again, testing on scraps to see if it's getting sharper! I ended up with this mess...However it didn't stay sharp for long, but hopefully it will work better for you- I swear I'm doing something wrong in my cutting. Still, I'm hoping Santa or the birthday fairy will bring me a "proper" one and save me some pennies spent on blades!