In the rules, there's an octave listed for the percussion instrument that is required. I don't know it off hand, but it makes up about 13 notes. Make those first, then add on to until you either get to the allowable limit or run out of time/supplies.
The required octave for the percussion instrument is G2 to G3 (if you don't know what that means, to put it in perspective, "Middle C" on a piano is C4 and the A 440 often used for tuning of string instruments is A4). And you will have to have an F# to be able to play the G major scale.