Mechanical music boxes are powered by clockwork springs. As the spring unwinds, the plucking force varies slightly.
The you are composing (Horror, Lo-Fi, Orchestral) music box soundfont
Whispers in the Gears: The Ultimate Guide to the Music Box Soundfont Mechanical music boxes are powered by clockwork springs
(missing some sharps), digital soundfonts often use "Viena" or similar software to pitch-shift and create a fully Preset Tuning music box soundfont
Here are the key features you should look for in a (SF2):
The sample should fade out naturally, mimicking the echo within the wooden music box housing.
A tiny amount of white noise or vinyl crackle can make a digital soundfont feel vintage.