I use Humes and Berg Enduro hard cases and the diameter of the case is the same as the diameter of the drum head. Mine fit perfect with the star-cast mounts on my Starclassics. I know you didn't ask about that but let me offer this...
For a hardware case. Look for a SKB or similar hard golf travel case. I got one on CL for $40 bucks and it's perfect for my hardware. Wheels on one end and a handle on the other. Holds everything. My hardware is very heavy...mostly Tama Road Pro stands. This works great. I should mention that the only thing that doesn't fit is my Roc N Soc throne top. I put that in the case with my floor tom. The base base goes in with the hardware.