There are several ways to connect external devices.
- It is possible to connect several video cables directly to each projector and simply switch to a different input.
- Using an additional capture card and the w’capture application it is possible to show your devices screen on any projector without having to switch projector inputs. In addition you can take screenshots from any device (video here). This can also be done wirelessly when combined with an Apple TV.
- It is possible to use common screen-sharing tools like TeamViewer or Lync to connect and share screens from other devices