Just an after thought, you may want to consider the Pi Zero. It only has one core, but they take less space. At $5 dollars apiece at Micro center, not a bad deal. Once catch, they only sell one at a time. You will also need to solve the lack of Ethernet and only micro USB connection. But that makes the project more fun solving the engineering problems.
You've got a funny idea there, clem! For "computing" there is not much "external" stuff you need except for a networking connection. So just plugging a cheap ethernet adapter into each pi zero should do the trick. Get yourself a TTL-serial adapter for configuration and debugging until the ethernet works....
To be honest I would rather use a RPi3 than a pi zero for the sheer power. I appreciate the idea but I think I am already on the right route. Thanks though!!!
