You may have some luck with model paint. Testors model paint makes a transparent blue spray paint. Here's the name of it. Transparent Blue 3 oz Spray Item:1257. They make it in multiple colors and can be found at most hobby shops like Hobby Lobby or Hobby Town USA.
2011 Space Gray 335i M Sedan
2011 Alpine White X5 xDrive 35d
JB4 Stage 2, BMS charge pipe, BMS downpipes, BMS intake