Does your hubby have a grinder of some sort? I used my dremmel tool to grind down several of my cones (it's a high rpm rotary tool kind of like a cordless drill, but a dremmel has a ton of different attachments such as cutters & grinders). Anyhow, I used my dremel to grind down the cone. I thought about putting a cutting disc on the dremel to cut the cone, but I thought grinding would give me a better looking end result with smoother edges. The finished cone is now a wee bit shorter, which allows a bigger opening on the tapered end, which in turn allows better airflow for cartos.
If your hubby has any power cutting or grinding tools, he can probably help you out CayCay.
A standard cone is on the left and the cone I grinded down is on the right