I'm building a jet engine out of pineapple cans.

I want to make an exoskeletal engine.

large exoskeletal engines have bearing problems, but at the model scale, it should be okay, and keeps me from the trickiness of a central shaft, right now I'm in the paper model stage (and have only modeled the condenser fans) and have lots of problems to work out in the actual fabrication (that would be easily solved with the right tools, but I don't have all of those)