[Bongle]

As for the legality, there's nothing stopping you from doing the whole shebang a few times for practice, then doing it again at the competition with your finely-honed mad skills of OI-upgrading. You can get around all the roadblocks first and find out the raw materials you need now rather than at the competition saying "oh crap, now I have to go a-running to radio shack. Does anyone know where a radio shack is?"

You may not be able to use the parts you make, but you can use your skills obtained from making the parts. I find that 90% of the time it takes to do anything for the first time is just stumbling about, looking for tools and parts.