I made this because getting up those hills can be easier with some tunes, and I didn't have the cash to buy one of the commercial ones. I really liked this too because it recycled things that weren't being used anyway - go green!
Step 1: Materials Needed:
Passive computer speakers (or active, but my available speakers were passive). The ones I used were branded Creative, and they were made by Cambridge Soundworks, so they were good quality. This helps.
Screwdriver - mine required Philips Head
Cassette tape case
Glue gun (or sewing implements, if preferred)
Mesh/screen to protect speaker