If you are interested in making your own thunder gourd, I have a tutorial available for $25 which includes shipping, one spring, two synthetic drumhead membranes, and a 3 page detailed instruction explaining the process and a list of all supplies needed to complete your own thunder gourd. Each additional srping is $5, and $1 for each synthetic drumhead. Feel free to email me any time with any questions.
As far as getting the gourd ready, I cut the bottom off with a miter saw then I sand the bottom down with a belt sander. To clean the inside of the gourd, I use the following wire brushes which I purchase at LOWES and haven't been able to find them anywhere else; a Kobalt 2" wire cup brush (coarse), and the 1" wire end brush. I do not recommend the wheels or anything bigger. The Erwin quick change bit holder (6" or 12") comes in handy to extend the length of the wire brushes, but also for quickly switching from one wire brush to another, or even adding another extension for those longer gourds. I do not soak the gourds in water, just simply wear a mask and clean them out. If you have any questions, just send me an email.
As far as getting the gourd ready, I cut the bottom off with a miter saw then I sand the bottom down with a belt sander. To clean the inside of the gourd, I use the following wire brushes which I purchase at LOWES and haven't been able to find them anywhere else; a Kobalt 2" wire cup brush (coarse), and the 1" wire end brush. I do not recommend the wheels or anything bigger. The Erwin quick change bit holder (6" or 12") comes in handy to extend the length of the wire brushes, but also for quickly switching from one wire brush to another, or even adding another extension for those longer gourds. I do not soak the gourds in water, just simply wear a mask and clean them out. If you have any questions, just send me an email. 
