The summer of 2021 I finally got fed up with my crappy ikea kitchen timer and decided to build my own.

You can find a build log in this Twitter thread.

Here's the bill of materials I ended up with:
Teensy 2.0

Adafruit 16x9 Charlieplexed PWM LED Matrix Driver
LED Charlieplexed Matrix - 9x16 LEDs - Warm White

Rotary Encoder
Solid Machined Metal Knob

PowerBoost 500 Charger
Lithium Ion Polymer Battery - 3.7v 2500mAh

Mini Magnet Feet for RGB LED Matrices
Piezo Buzzer

I supplemented some additional fasteners to screw into the mini magnet feet from the front clamping the case layers together.

The schematic is available in the assets folder, as is the templates I used to laser cut the enclosure from 3mm acrylic.