Agreed. Hard to find cans with 5" diameters though. 4" is no problem. Maybe juice cans would work.Empty can heated on a stovetop works great, and takes 10 seconds to do.
EDIT: rhumbagirl beat me to it.
I bought a tool for this and it works perfectly. https://www.sweetwater.com/store/detail/HOLECUTTER--bass-drum-os-hole-cutter-for-bass-drumheads