I did not want to make my own, so I bought these and tried them earlier (they arrived in 3 days using first class mail). The fit inside a 7mm tube and the shank fits in a Dremel or drill. I bought them to sand/polish the inside of semi-transparent and transparent barrels.
This company has some other interesting things for penturners.
Mandrel - Split Mandrel 3/32" shank | Cool Tools
Metal Clay & Supplies | Cool Tools
As long as you have two open ends (which I understand is not always the case), you can flip the barrel around and sand/polish from the other side.
They are $2.25 each ..seemed like a small risk. So far I like them.
Have fun!
This company has some other interesting things for penturners.
Mandrel - Split Mandrel 3/32" shank | Cool Tools
Metal Clay & Supplies | Cool Tools
As long as you have two open ends (which I understand is not always the case), you can flip the barrel around and sand/polish from the other side.
They are $2.25 each ..seemed like a small risk. So far I like them.
Have fun!