need to make a small trackpad

I need to create a postage stamp size trackpad in order to make a product I am working on, for my current proto type i have an (ergonomictouchpad <a href="https://www.ergonomictouchpad.com/mini_touchpad.php" target="_blank" rel="nofollow noopener noreferrer">The Mini Touchpad</a>) Due to its price and its inability to be completely modefied to fit in the chasis I need it to be in, does anyone know a way to create a touchpad made only for scrolling. (Much like the MIT project Nailo <a href="https://news.mit.edu/2015/wearable-thumbnail-sensor-controls-digital-devices-0417" target="_blank" rel="nofollow noopener noreferrer">Thumbnail track pad | MIT News | Massachusetts Institute of Technology</a>)