If you wish to speak to a sneaker manufacturer, the first thing you must do is to get them to sign a non disclosure agreement. Be very adamant about this, as this does offer you some protection.Also ensure that the person signing the document, has the authority to do so, else you have nothing.

The other route is off course to file a provisional patent, but then you have 1 year in which to lodge your final patent, or PCT patent. This protects you in the manner that once you have the provisional patent, no one can lodge a patent with your idea, ever, even if you allow the provisional patent to lapse.

I suggest you talk to either Adams & Adams or Spoor and Fischer. The first meeting is no charge anyway, but will give you a far better understanding what to do next. A provisional will set you back between R4 and R20K depending on the complexity.