I chose a PC speaker MS-77 manufactured by Elecom for this project. It is separated in left and right channels and the amplifier was built into the right one. To built the MP3 player into the case, open the case and remove the amplifier. The rear panel was fixed in ultrasonic welding. I drilled some holes to the rear panel, and pulled and remove it. The internals are held by only rear panel and there was nothing to fix inside the case so that I bonded four studs to the corners to fix a rear panel (Photo 2a). A slot (2.5 x 25mm) is required on the case to insert a memory card. Because the material is acrylic resin, it should work with care of crack and chip (Photo 2b). The indicator lamp (two color chip LED) is embedded into a hole that drilled at bottom of the case.……