This spectrometer is small enough to fit in your pocket and can be used on your mobile phone with a web based spectrometer like spectro-web. I also added a case to protect it from dust and scratches.

I recommend to try the 0.6 mm slit at first, then adjust if needed - they are separate and interchangeable, only the slit cover needs to be printed.

The only extra material needed is a DVD (CD, Blu-Ray, etc. won't work as they have different track pitch, leading to different diffraction), see this post for instructions on how to prepare it.

Use black filament or spray paint black (as in the pictures) to reduce reflection inside.

This is a toy, not a scientific instrument, aimed at curious people.