FWIW, I made my own keys out of a hack saw blade I ground down on my bench grinder. Took about 10 minutes for each "key". The blade is a perfect thickness and of course I ground off the side with the teeth to narrow it down .

Do a search on radio keys until you find the post with a picture of the keys to print out as a guide, break a hacksaw blade in two and grind away. The notch doesn't have to be perfect and be sure to smooth the edges with a file or sand paper.