I made this low voltage amplifier using LM386 which can be work on 9v battery easily available at home . In this I connect speaker as the output device and I take bluetooth-usb Module as the input device  . For the packaging/outer box I use the old wooden box (which was a actually a wedding invitation) . I choose wood because it is  naturally non-resonant so energizing a speaker box with musical vibrations will result in minimal distortion. Wood has a high density. It has been used for centuries to help amplify a richer, clearer sound in instruments from guitars to grand pianos It’s naturally strong and stiff also it is easy to craft with the tools available at home with that reflection of sound are less in wood than with plastic or metal . The idea was to create a low budget all purpose , potable audio device so I made this in around 2.5$ .The big credit goes to this wonderful IC LM386 which is available at very low price one can easily get this around 0.3$ in India .
Material Used : 
1. IC LM386 
2. Capacitor (220uf and 100uf)
3. Resistor (10Ω)
4. light Emitting Diode's (LED's)
5. Soldering iron and soldering wire 
6. Ceramic Capacitor (o.o1uf )
7. Speaker's 
8. Potentiometer (5k)
9. Bluetooth-Usb Module 
10. 9v Battery , Connecting Wire & Circuit Board
11. Voltage Regulator LM7805