why do the white guitars get darker in the highlight? all the others are lighter...

I love guitars too, maybe have a look and comment on mine I drew . Like someone commented on mine you have forgot to put strings on them. Maybe it's just me but it would be really hard to make the strings look gradually thinner. only thing I can see wrong is the colour of the frets. They seem too white. I really like these though.

The highlights on the left sides of the guitar look messily done. Almost like you used the line tool to create the shade. Make it more round and fit the shape of the guitar. Same with the white highlights.

Tnahks Soda e Chinecafon i will imporove this.
=D

bacana! acho que você poderia trabalhar um pouco melhor na mão e no braço delas!
bom trabalho

Wow, that's pretty amazing.