A spectroscope for UV-IR spectrometry.

I used an ELP USB-camera with and adjustable lens (this brand, they also have an Alieexpress store: https://www.webcamerausb.com/) and a piece of a broken CD as a diffraction grating. In order to see infrared, make sure your camera doesn't have an IR filter. The camera housing is taken apart and attached to the spectroscope using the front panel. The CD is held in place with a holder that can be rotated to any angle using an M2 screw. I recommend inserting a brass insert into the CD holder for this purpose as well. The entrace is a 0.8 mm slit, that can be narrowed using slit inserts down to 0.1 mm. A Toslink optical cable can be attached to the ligt entrance to make pointing at a light source easier.
I uploaded a version with a 25 degree angle between camera and slit, and a version with a 35 degree angle between the camera and slit ("increase angle").
I also uploaded the FreeCAD files if you want to make adjustments. I'm still a novice at CAD, so they aren't the easiest to modify though.

I reccomend the user-friendly software Theremino Spectrometer to interpret the spectra: https://www.theremino.com/en/downloads/automation (scroll down on this page until ou see the spectrometer section)

If you want to try VIS-IR absorption spectrometry, I recommend downloading this cuvette holder from Gaudilabs which works with the same Toslink cable: https://github.com/GaudiLabs/3DFiberSpectrometer/tree/main/CuvetteHolder/STL

The spectrum in the images is from a neon bulb.