There are many interesting DIY projects that you can undertake, but, as seen on Tindie’s “Sound” section, DIY musical devices are, in my opinion, some of the most interesting. The PCLONE2 percussion synthesizer, as seen in the video below, is no exception and imitates the 80s-era PC-2 synthesizer using modern components. It has a selection of knobs and switches to control the sound generated, and an area toward the bottom that you can tap to trigger the sound. It can also be triggered from an external signal.
In other words, it’s like an extremely advanced version of tapping on your desk or seat to occupy yourself. Perhaps you could bring one of these to the next lecture you have to attend to let the speaker know how well he or she is engaging the audience.
The device comes unassembled, and is described as an “intermediate complexity kit for experienced solderers.” If you don’t feel up to the task, perhaps one of the other interesting musical offerings on the “Hotchk155” store would be a better challenge!