Sorry for the lack of updates! My grandmother past away the other day at the age of 91 so I was constantly in and out of the hospital visiting her. Anyhow, here's a quick tip on how to spin cylindrical parts. You can use a Dremel or a power screwdriver to get the job done.
For materials, you can use anything from wood (choose a soft type), plastic tubes, and hardened clay. The key is to find the center point in order to insert a metal rod into. This is where the Dremel or screwdriver will lock onto for spinning. Even the slightest inaccuracy in centering the piece will cause a wobble when spinning. This will cause uneven sanding and/or carving.
The best way to combat this is to start by scratch building your piece with some kind of hollow rod and then build your object off of that rod. Then you'll know for sure your piece is centered.
I know, this is a shitty tutorial due to the lack of pics but I literally flipped through my phone pics to find something decent to post. I'll try to do better tutorials in the future.
Okay, once you've centered your piece with a rod you can now start spinning it on the power tool. While the object is spinning, try to start with a medium setting so the object doesn't spin too fast. If the object is spinning too fast and you have a filer grinding at it, it can heat up really quick and even melt if the object is plastic. Also, it will magnify the wobbles.
You can see in the first pic that the object is actually spinning with no wobble.You can also see that I have a metal file which I use to manipulate the shape. Just use your imagination on what type of tools to use. Sand paper, nail filer....etc.