I was very impressed by John's model at Edinburgh. This was to be a turning body submarine which would cross the atlantic in 28 hours!
The spiral is done with windscreen wiper rubber and the body revolves very nicely.
John must be working his way (like me) through the really useful book "The Garrett Enigma and the early submarine pioneers." by Paul Bowers.
This covers a large range of early submarines and includes good drawings.