Basic Switch Box For USB Devices
The Aten 2-Port USB 2.0 Peripheral Switch US-221 provide a way to share USB devices like printers, scanners, or external disk drives with multiple computers. Before access can occur, however, the user must push a button on the US-221 device. Shortly afterward, Windows recognizes the shared device and it becomes available for use. This also makes the onerous task of plugging and unplugging USB cables unnecessary. The US-221 supports the faster USB 2.0 specification, which makes it suitable for sharing external hard disks and CD/DVD burners as well. The US-221 costs about $37 (30 Euro), a four-port model, the US-421 costs about $55 (45 Euro; neither model appears to be available for sale in the US at present).
Sharing USB-Devices among multiple PCs
Two computers can use the same USB device
One printer for two PCs
The USB Switch principle: 2 PCs share a single printer between them