A Brief History
Cigar box instruments date back to the 1800's, when cigars began to be packaged in smaller units in handy wooden boxes. The great depression caused an increase in the popularity of handmade instruments as an affordable option.
There are a lot of wonderful resources online, including plans from a 1920's magazine and some mail order kit instructions. The best resource I found was Steven Miller's step by step guide. Anyone considering making a cigar box uke should check out his guide here . This instructable is really based on Steven Miller's guide with added details and measurements for guidance. A cigar box can become virtually any stringed instrument - guitars, fiddles, mandolins, banjos. For more cigar box ideas and free plans check out Cigar Box Nation .
Step 1: Stuff You Need
Cigar Box. If you have a choice, find one of solid wood. I found a cedar box with a plywood base. I paid 4$ for mine, but it shouldn't really cost more than 2$.
Wood for the neck and bridge - for a concert sized ukulele I needed a 14 x 2 x 2.5 inch block for the neck and head. The bridge will be about 2.5 x .5 x .75 inches. I used walnut, but any hardwood will do.
Wood for the lid supports: the cigar box will vibrate with the strings. The inside of the box must be braced with a wood light enough to allow the box to be springy but strong enough to keep it from warping. Steve Miller suggests spruce, but I used pine since I had some lying around.
Wood for the inside supports: These will go around the edges of the box for added strength and for a place to anchor the neck. I used some left over walnut.
Wood for the fretboard: I chose red oak. It will need to be approximately the length of the neck and ~1/8 thick.
Material for the saddle and nut: I used dominos, which I cut down to size. Another type of hard plastic or ebony will also work.
Material for the frets: I actually bought brass welding wire for the frets, but ended up inlaying crushed turquoise instead. If you choose to inlay crushed stone the ukulele will essentially be fretless, which will change the way you play it.
Fret markers: Ukes are usually marked at the 5th, 7th, and 10th frets. Pearl dots are traditional. I used a 3/8" wooden dowel.
Ukulele strings: see your local music store.
Tuners (set of 4): I took the tuners from a busted kid's electric guitar I got at a thrift shop. You can also buy them new from a music store. They cost about 14$ for cheap ones up to 50$ for fancy.
Tung oil and mineral spirits (optional)
Steel Wool 0000 (optional)
Drill press (for the sound hole a large diameter bit is required)
Dremel (I used the plastic cutting and engraving attachments)
Note about tools: I was lucky to have access to a woodshop, powertools, and someone who kept me from cutting off all of my fingers. With some ingenuity much of this can be done with hand tools and patience.