Perhaps it's not what the OP is looking for, but others reading these answers might be looking for simple solutions for creating 3D-printable designs.
Minecraft is a 3D editor that a 7-year-old can use. And exporting the models into a printable format with MIneways is also child's play. Honestly, if one were to add a few blocks to Minecraft (such as half-cubes bisected diagonally to allow for more "rounded" shapes), it could actually be a very effective and simple tool for making basic 3D models. Not a professional engineering tool, obviously, but if someone is daunted by spending months learning a serious tool, they can simply fire up Minecraft and Mineways and be printing their creations in 10 minutes.
With some 1/4" to 3.5 mm adapters and 3.5 mm cable, you can run a signal to 4 PC speaker systems. The individual gain controls for each line out allow you to compensate for the specific loss in each line due to varying cable lengths.
If you buy the right speaker systems, they could also have local aux in jacks in case you want to listen to an ipod or something. You might want to check whether it replaces or is layered onto the main input, though.
Reactor error - core dumped!