It has been a while since I have worked on this project. One of the last attempts I did a while ago utilized a bit of release wax and PVA on an aluminum tube. The idea was to create a part with better tolerances, however that part seems to be permanently bonded to the mandrel. It was hoped that exposure to cold would shrink the aluminum mandrel more than the carbon, however it just wasn't enough.
Another attempt after that utilized the paper and tape method using an aluminum mandrel. This gave a nice part with good concentricity, but alas the ID was too large to be useful.
Today I decided to take a step back and make some fiber glass parts. I was hoping to have gotten the first carbon part fairly quickly, but it seems there is enough iteration that needs to happen that the first rocket might end up using fiberglass to reduce the cost of experimenting.
Instead of using packaging tape as my release layer with paper under it, I am trying to use a section of plastic film from a page protector. A section that allowed for ~2 wraps around the mandrel was cut from the protector, and wrapped around the mandrel. The film was then taped once in the center with a small piece of scotch tape. I am hoping that this with both be easy to remove, as well as not so thick as to make the part useless.