This was my first real attempt at luthiery. I had built a bass guitar and hammer dulcimer, both from kits, but never attempting anything from scratch before. The end result was a somewhat odd cross between a cello and a tenor bass. It's tuned in 4ths like a tenor bass (ADGC), but has a lot of cello-like features. The neck is mahogany, the fretboard is ebony, and the body is mahogany and paduak with a purple heart plate on top. Initially, the instrument had a standard piezoelectric cello pickup on the bridge, but I didn't like the sound (very nasal, probably due to the stiffness of the body; purple heart is dense!). I couldn't use magnetic pickups since most cello strings are non-ferrous which left me with the possibility of optical pickups. I ended up using a system from Lightwave Systems which sounds great, but does have some issues. Basically, it's very challenging to mount the pickups such that bowing angle doesn't affect the amplitude of the signal. This is because the pickups only detect string motion along one axis and bow angle changes the amount of string displacement along that axis. With only a single detector per string, I couldn't completely solve this problem, although mounting the pickups such that their orientations follow the curvature of the fretboard seems to minimize the issue. Keeping the curvature of the fretboard low (large radius) also helps since it limits the range of bowing angles (especially for the middle two strings).
Here are some photos of the instrument during various stages of construction. The quality of some of the images is kind of crappy, but keep in mind that I started building this thing in 2001 when digital cameras weren't that good or cheap!