Use this schematic to mount the device. Pay attention: some stuff isn't in Fritzing libraries and could be different. Read the notes.

• The display uses 3 pins for SPI and sensors 2 pins for I2C. 3 pins for pushbuttons (up, down, enter). 2 pins are connected in the front to header pins, they are analog pins.
• Solder the XIAO in the topside but take care of align the perfboard holes. XIAO ESP32C3 has two pads in the bottom to connect the battery and you must solder them in the bottom, it's a little tricky.

I've used M3x10. I've need some iterations to fit all the componentes, this is also tricky. If you made one maybe is better to print the case in first place to align correctly with electronics and glue them later. In my case I didn't follow this way because I designed the pieces after glue components and take the measures, As you can see the design includes a hole for a wrist strap. And the same color than pla, I was lucky with that.

TO-DO: 

• Refine the code, main menu, badge and spectrometer are ok, the rest are in construction.
• Monitor battery voltage and display it via an indicator.
• Include a buzzer.
• Add pending functions like tester/oscilloscope.
• New features as they come to mind.