want to build miniature sound system

What you can do, is build one complete box that looks like several bins stacked from the front, but is all hollow inside. Then mount a Hi-fi mini subwoofer in the back of it, and you should have enough box volume for it to work. Aurasound have some nice 4 and 5 inch sub drivers that work in small sealed boxes.

For midtops, you can use some tiny 2 or 3 inch full-range drivers in small models of mid-horns. The horn will be too small to do any actual horn loading, but will look the part. The tweeter horns and bullets above, can be purely cosmetic, as the full-rangers will play plenty of treble. Fountek are a good manufacturer, also Visaton.

You can power the whole thing from one of the small 2.1 channel class D amp boards based on the TPA3116 chip. They are cheap from China....oh...might be a problem there ;)