here's everything you need:
- housing printed on a 3D printer
-arduino nano (can be a clone)
-universal PCB 50x70mm
- i2c OLED display 1.3" (any color)
-6x button 6x6mm
-goldpin famale 2x15
-goldpin male 1x4
-buzzer
-slide switch
-4x screws (M2.5, can be x10 or x16 or x20 or x25)
-optional LED and some capacitor

full assembly instructions and arduino code, can be found here: https://www.instructables.com/Zdrapson-Mk1/