In our never ending search for cigar box guitar plans, we stumbled across these very simple instructions to build a one-string bass with a "whamola" style lever as the tuner. The plans come from a 1970's children's book. (I've lost the book's name over the years.)
Although the general idea for the box bass is great, the instructions are quite vague in these plans. It would be great to have an updated version of this plan with measurement details and demo videos. If you feel inspired, post them in the comments below.