Spectrometer construction
Public Lab has developed multiple open source Do-It-Yourself spectrometer designs. Choose between the following:
Desktop Spectrometry Kit - a precise and inexpensive webcam-based design built in a conduit box
Foldable Mini-spectrometer - a small paper model which attaches to a smartphone
Both can be made from simple, easy to find materials for very little money. You can also purchase a kit to get started faster at the Public Lab Store