This is a list of the parts that you will need for this project; specific parts have a link of where they can be purchased (it is recommended that you use these specific parts as other similar parts may need an assembly that differs from the instructions given here), and all other parts can be purchased from an electronics components store:
The Raspberry Pi
A USB storage device to store a media library (it is possible to use a hard drive; however, to keep the wiring simple, it is advisable that you use a memory stick)
A Wi-Fi adapter (uk.rs-online.com/web/p/product/7603621/)
A flight case (http://www.maplin.co.uk/p/flight-case-triple-pack-with-dividers-n50ju)
A length of 26 AWG wire
A length of 32 AWG wire
A 3.5 mm stereo audio connector
A strip of terminal blocks
Eight 20 mm M3 screws, washers, and nuts
Two full-range speakers (http://cpc.farnell.com/visaton/2133/speaker-full-range-5-60w-black/dp/LS02184)
Two mono amplifier modules (http://cpc.farnell...