Considering the DIY nature of the build and need for constant modifications, we came up with a modular design for the housing. It’s small, everything fits neatly and at the same time gives easy access to different sections of the device for modifications. The device is split into four different sections -

1. Nozzle - This section houses the excitation source, LED.

2. Sensing Unit - The spectrometer and the optical filter sits in this section.

3. Processing Unit - It houses other main electronics which includes the microcontroller, bluetooth module, battery, and the buck booster.

4. Lid - There are no components in this section, once removed it provides access to battery connector for charging.

All the sections easily press fit into a neat little device that looks good and can easily be carried in a pocket. :)

All the design files can be downloaded from the ‘files’ section of this document. The files are available in ready to 3D print .stl file format and also in neutral file format for easy modifications! The parts designed are optimised for 3D printing and there is a file named ‘preferred_print_orientation’ that shows orientation of the parts on print bed while printing.