I really don't remember getting the idea for the presta tube, but my first brass
mod had it with a spring and before that I had just a screw in a hole which was very sloppy. You can get all the parts in the states, bike stores have old presta tubes and nuts from changing out inner tubes, and the metric tubing is a little tricky but can be found on ebay. The rest is SAE and available in hardware stores, plus magnets from ebay or K&J magnetics if ebay isn't working out with price or availability. It's pretty easy to source everything.
