Here are my headcannons! (Click the links to listen to the sound of the instruments)
Blue: Ocarina
Red: Harmonica
Yellow: Accordion
TSC: Classical Guitar
TDL: Stylophone
TCO: Electric bass
Victim: Bass flute
Orange/MT: Trombone
Gold: Glockenspiel
Navy Blue/Dark Blue: Cello
Pink/Orchid: Piano