UPDATE:: there are lots of better ways to do this. I just documented mine. I know this compromises pretty much everything that a good guitar should have. the thing is, my guitar didn't have those qualities. so that's why I did it. I've actually already gutted and thrown out the guitar (kept the insides for replacements, see), but it would work if you needed it to.
Step 1: Remove the Strings of the Guitar
Step 2: Remove the Neck
note- there may be some glue holding it on. mine was old and has suffered some damage, so the glue was no longer holding.
Step 3: Remove the Pickguard
Step 4: Remove Part of the Neck
you're going to want to take off some of the end of the neck. it's hard to explain, so look at the picture.
Step 5: Attach the Hinge
Step 6: Mark and Screw the Hinge Into the Guitar Body
Step 7: Put the Electronics Back In
Step 8: String Winder
the hole for the axle is drilled straight through. I would reccomend using a drill press. I don't have one. my axle is crooked. get my point?
the holes for the pins go in the sides. you might want to make a few, because you never know what position your cylinder might end up in.
the holes for the strings are drilled at an angle. they are this way because it causes less stress for the strings.
sorry about the ms schematics, this step took both hands. also, I forgot to take pictures.
Step 9: Mount on Guitar
Step 10: I've Made It, How Do I Use It?
to keep the neck down while playing, screw in the top two screws originally used to hold on the neck and tune. when you want to collapse it, unscrew them, then roll the cylinder until the strings are wound around it and are kept out of place.
I don't have an original picture for this step. suck it up.
Step 11: Ending Notes
this guitar doesn't hold a tune. my guitar didn't hold a tune before, so that might be it, but be warned.
you may want to add side guards to the string organizer. on my design, the strings would fall off the side of the cylinder.
I know this is not an original idea. but it's original because I am the first to DIY this guitar (as opposed to the commercially available one).
this method doesn't work for fused neck guitars. only bolted ones.
you can endlessly adapt this method. I'm just documenting mine. for instance, ironsmiter added this comment (this is just an excerpt):
Step 4 ; It's usually called a Rabbet. Sometimes, mistaken for a Dado(which is really only a rabbet on the face side of the board, rather than the side).
Step 5 ; I think a Door hinge(maybe a little overkill) would be plenty strong, and a brass one might look nice too.
By using 2 dead-bolts on the back, and a piece of velcro strap, you could avoid the whole string winder issue. Basically, loosen the strings a bit with the tuning pegs, wrap the lower neck once with the velcro strap, undo the deadbolts, and fold. The strap should hold the strings pretty well in place, and the dead bolts should resist the folding forces well, when re-tuning the guitar.
I really like the strap idea- the string winder seemed like a good idea, but it doesn't work as well as i'd hoped. this just reiterates the idea that this isn't set in stone, and it's an endlessly changeable project.