This is a simple but very effective way to remove those stuck on knobs. If your knobs are hard to remove check first to see if they have a set screw before doing this.

Just wrap a rag under and around the knob and with even pressure, gently pull it up and off. 

All you need is a couple pieces of scrap 2x4, glue, jig saw, padding and some sandpaper.

 

1. Just draw a half circle on two separate pieces of 2x4 (use the full 3 1/2 inch width) and cut them out with a jig saw or whatever saw you have that can cut a curve.  it doesn't have to be perfect, you can sand out any rough areas

 

2. Glue them together and clamp or set something heavy on them while they dry.  Elmer's white glue will work fine.

 

3. After they are dry (12 hours) sand them so they have a nice smooth feel and round all the edges.

 

4. Now the hard part, hollowing out the center "U" shape area for the guitar neck.  You can put some 50-80 grit sandpaper on a baseball bat and run it back and forth or of you have the tools you can cut slots in varying depths in the shape of a "U", break them out and then sand smooth.  You can also cut some of the wood away before you glue them to save you some time.

 

5. Cover the "U" shape area with something that will protect the neck.  A good choice is the non-slip rubber stuff you put under rugs and such.