Thanks to forums user jim_lee for sending this in, with a great write-up on his blog detailing the entire process and inspiration behind the project, along with all the code to power this homemade RPN calculator hosted here on GitHub, and 3D-printer files here on Thingiverse.
Featured Adafruit Products!
2.8″ TFT Touch Shield for Arduino w/Capacitive Touch: Add some sizzle to your Arduino project with a beautiful large touchscreen display shield with built in microSD card connection and a capacitive touchscreen. This TFT display is big (2.8″ diagonal) bright (4 white-LED backlight) and colorful (18-bit 262,000 different shades)! 240×320 pixels with individual pixel control. Read more.
Teensy 3.2 + header: Teensy 3.2 is a small, breadboard-friendly development board designed by Paul Stoffregen and PJRC. Teensy 3.2 brings a low-cost 32 bit ARM Cortex-M4 platform to hobbyists, students and engineers, using an adapted version of the Arduino IDE (Teensyduino) or programming directly in C language. Teensy 3.2 is an upgrade over 3.1! Teensy 3.2 is a drop-in replacement upgrade for 3.1 and can run any sketches designed for 3.1. Read more.