I haven't found any Rustoleum Spruce Green (as effectively, it never was available to Canada) but I think I have found a suitable alternate color...
It's called ''Spring green'' and made by Excel - Colour Vision...
I have looked at some electronics stores and at Wal-Mart but couldn't find anything that even sounded like masking fluid. I bought some rubber glue (kids craft section) and have made a couple of tests to see if it will work... I'll tell you all soon how it went 
Thanks for all the answers you are all of great help!