Some PVC Piping, bicycle pump, PVC pipe welder, some valves, superglue, and a bicycle nib (part you hook a pump to) and there you go. Wal Mart sells plush angry birds.
I understand how to make a potato gun(im irish)lol, maybe it could be electronically target controled. like the little usb missle lanchers you can buy for your desk. or maybe an electric chair for Furby's would be better!
Controlling it with usb is'nt that hard actually, simply hook up a microcontroller with usb support and modify one of the many examples to be found on the internet to create the pc software.
I just made a project using the 18f4550 and the mikroc usb library, and it turns out that you can get it up and running well within a hour.
You might also want to add some face recognition (with the use of a webcam perhaps) to enable it to track people around the office.
