Keep in mind, for windows 7+ I had to change the friendly names of each web cam so that Processing can address each one consistently. Here is a tutorial:

Also, here is an Instructable to hack the power supply: 

The actual build will probably vary so I don't have any real details about that up here.. 

The code is fairly modular and you should be able to reduce/increase the number of webcams or shutters/servos by changing only 2 or 3 variables.

​I would also recommend trying an adjustment in the code: instead of counting blue pixels to refresh shutters according to amount of movement, build an array that drops that oldest pixels so that you don't have too many servos moving at once (big power surge). I might try that later and update the GitHub..