Electric guitar drawn in FreeCAD with a freehand polygon, extruded, with top face corners rounded three degrees.
UPDATE: Added tone and volume knobs, pick guard, tuning posts, and strings. (bridge test time!!!)
If bridging doesn't work, maybe superglue some real string or fishing line would be good. If you print 1.75mm, raw filament would work too.
The basic guitar is simple to print, but it's quite large. If you want a keychain sized guitar, scale it down to around 15%.
The detailed guitar is a scaled down version of the basic guitar with details including strings printed as a bridge.
I printed this in translucent blue. My nozzle size is 0.6mm with layer height of 0.55mm in PLA.