See here for Part 1 of our trigger discussion.
We concluded our Building Day with a discussion of trigger options. We decided to try out the remote/switch system with CHDK and a USB trigger. The trigger is powered by one AAA battery, which solves our concerns about rewiring our switch to an undetermined (battery, laptop, electrical outlet) power supply that are using to send an electrical signal to the cameras. So the unlikelihood of fried digital cameras made this option that much more attractive.
We also hoped that this system would minimize the kind of physical troubleshooting that the mechanical method would require, such as adding the correct tension to trigger hammers by using materials (rubber bands, bungee cords, etc.) that degrade over time. Also, we wouldn’t have to design and cut extra pieces with equipment that we don’t have regular access to.