Complete instructions for this episode of Weekend Projects can be found at

http://makeprojects.com/Project/MonoBox+Powered+Speaker/2396/1

Learn the basics of audio amplification with a portable powered speaker that you build yourself. With some light soldering and clear step-by-step instructions, you will first wire up a simple amplifier circuit using a popular IC. Then, outfit an enclosure with the speaker you want, and design the enclosure to suit your style. Lastly, plug in your MP3 player or any 1/8″ line-in source and rock out!