We are not sure if you really need a laser to build [HoPE’s] Laser harp. It is just some photovoltaic cells, and there is an Arduino to generate tones based on the signal. Nevertheless, you still need to excite the photocell in some way, and lasers are now cheap enough.
Mechanically, the device is a very large wooden structure. There are six lasers aligned with six light sensors. Each sensor is read by an analog input pin on the Arduino equipped with a music generation shield. We have seen many such things in the past, but this simple thing is very attractive.
We used the copper tape writing technique ourselves, and it was very effective. Tape is usually used for stained glass work and sticks to many surfaces. You can solder to it and solder the overlap where you need to connect. The result is usually as good as a simple single-sided PCB.
The code attached to the post is fairly simple, and MIDI shielding does most of the work. It should also be able to easily create some truly impressive musical effects with some additional coding.
If you want a standalone version with an artistic touch, check out the previous Hackaday Prize entry. We have seen that some of them have varying levels of complexity.