Portable speaker

Speaker box using 2.5W 4ohm speaker from an old PC monitor and an audio amplifier with volume control based on Pam8403 chip (2 Channels 3 W Digital Power Class D Audio Amplifier Board, USB DC 5 V).
I used two rectangular speaker from an old PC monitor enclosed in a box with an audio amplifier powerd by a micro usb connector.
The box is designed in two pieces.
To assemble the two parts I used 2.5mm screw with brass knurled insert nut recycled from an old Notebook PC.
On one side of the box there are two 3mm holes used to attach two pin because I've mounted the box on the back of the PC monitor using two brackets screwed in the wall mount holes.