Punty Level
Automated sonic level for glassblowing instruction.
In glassblowing, molten glass is collected on the end of a solid steel rod (called a punty) or an open cylinder (called a pipe). After gathering glass from the furnace, glassblowers (or gaffers) rotate pipes/punties to control the material and keep it on center. Beginner glassblowers typically struggle to keep these tools level in rotation while moving through the shop. If held too high after gathering, glass will flow back onto the pipe/punty. This restricts the amount of usable material (because the glass then cannot be removed intact). If held too low, depending on its level of heat, glass can drip off the end of the pipe/punty. 
I was approached by Associate Professor Helen Lee, Head of Glass in the University of Wisconsin-Madison Art Dept., who was interested in developing a tool that could attach to a pipe/punty and emit a tone based on the degree of deviation from the level plane.
For the electronics, I decided to use an Adafruit Feather microcontroller. The Feather provides a very small footprint, while still having nearly the same full functionality of a full sized Arduino UNO (serial debugging saved me a lot of time!). I used a 14-bit Adafruit I2C accelerometer to detect the angle of inclination and a small piezoelectric element to produce a tone.
One of the most challenging aspects of the electronics design for this project was getting a loud enough tone from the small piezo. Since the Feather runs entirely with 3.3V power and I needed to use a small lithium ion battery, I ended up using a very low power DC/DC converter to boost the voltage going to the piezo up to its maximum rating of 12V. This produces a tone that is loud enough to hear over the ambient noise in the studio.
To increase the accessibility of this tool/project for other glass instructors, I designed the body of the level to be easily 3D printed. The holder is essentially a clamp that can accept a large range of different pipe/punty diameters. The hinges are printed in place, meaning that there is no assembly once the print is complete (other than the electronics). The Punty Level is quite small, roughly the size of a coffee mug, and can easily be mounted on the far end of the pipe/punty to minimize awkwardness for the gaffer. Rather than designing a finicky latch system, I decided to make a lip which can be secured with a rubber band.
Ben Orozco (neon artist) demonstrates the use of the punty level in the UW Glass Lab.

In this video, Ben demonstrates how the pitch shifts depending on whether the pipe is higher or lower than level.

This project taught me a lot about designing 3D printed objects, and more than I ever wanted to know about increasing the volume of small piezo elements.
I have a GitHub page for the project here (instructions are in the wiki) and a Thingiverse part for the holder here.