I took a picture of a guitar to a coping store (like Staples) and had them blow it up to a full size quitar.. layed it diagonal on a plain black background fabric and then free motion quilted musical notes and stars all over the quilt. using black thread. I also use gold (or yekkow plain thread) and silver metalic thread on the quitar for the strings and bars on the guitar. This I did before it was appliqued onto the background, I traced the quitar onto sew in interfacing (light weight) then sewing on the lines that I traced on the interfacing sewing it to the right side of the guitar fabric then make a slit in the interfacing and turn the fabric right side out this takes care of the seam allowance and makes it to where you can decorate the guitar before applique to the background fabric... I took pictures of the quilt but have not idea where they are... Hope this gives you some ideas. The guitar looked real from a distance.
Junie