My friend and collaborator Sudhu Tewari reverse engineered a commercial version of an electronic bow (Ebow) for a commission in 2010. He and I bought parts in bulk and spent a few days prototyping these instruments in his basement. Several months later I decided to recycle the idea for my MFA installation. I refined the design and built 9 more, each including a different sized bass or guitar string that were tuned to vibrate at different harmonics.
These instruments are the second generation of the work we have done with vibrating strings and are comprised entirely from hand-fabricated parts (except the tuning machines). The whole project took about two months to complete.
The boards I used for these are reclaimed (actual) 2x4s that were salvaged from some local architectural renovation. They are old growth, douglas fir with very small and numerous rings of growth. I counted over 100 in several of them. I really enjoy knowing that the sounds being emitted from these strings are passing through the layers of the wood which, of course, represent the number of years the tree was alive. This adds layers of meaning to the sound that is resonating through, and being amplified by, the boards.
Turn your speakers up to really hear the different vibrations.