To make your cigar box guitar distinctive you can create your own headstock shape. You can paint it or glue a paper picture or photo onto it. Or, in keeping with the rustic nature of the instrument, you can keep it simple.
The important aspect of the headstock is to have the thickness and width to hold the 2 tuners.
To create the headstock draw a line 6mm above the nut slot and extend the pencil line down the sides of the neck on each side. Measure the thickness of the neck and with a ruler, or marking gauge, mark a centreline line at half the thickness along the sides of the neck and along the end of the neck.
Saw along the line (6mm above the nut) at 45 degrees until the saw cut reaches the centreline you drew around the headstock. Now, saw down from the end of the neck, along the centreline until you connect the cut with the 45 degree cut. This cutaway section of the headstock creates the “headstock angle” that provides the down force for the strings.

Cigar Box Guitar Headstock clamping
You will now have a rectangular piece of the neck with a 45 degree “wedge” at the end. Take this piece and glue it to the back of the neck to create a thicker headstock. When the glue has dried, sand the top face and back face of the headstock smooth.