Arduino Weight Scale

This is my final project from my Sensors & Measurements course. We had to make it using an Arduino kit and household items. Although it wasn't a particularly challenging project, making a weight scale using a basic Arduino kit isn't something I would normally consider building.

The scale is built out of a 3D-printed PLA base (we were permitted to print up to 25g of material), four pen cartridges, four pen springs, and a rigid cardboard platform. An ultrasonic sensor was used to measure the displacement of the platform caused by the weight of the test mass. The raw data from the scale was calibrated using known masses and achieved an overall error of 4.6% of the full-scale output of 1800g. While it's fairly inaccurate compared to an actual scale, I expected it to perform far worse given the use of random household objects and a cheap sensor, but I was surprised by how it turned out.