With exams behind him [Adam Greig] had time to make a Nerf sentry gun. It’s actually quite easy to pull everything together. He’s got a netbook running Motion, an open source motion sensing program ...

Did you know the muzzle velocity of a NERF dart out of a toy gun? Neither did [MJHanagan] until he did all sorts of measurement. And now we all know: between 35 and 40 miles per hour (around 60 km/h).

Fans of Valve’s Portal series of games will appreciate this real-life Portal Turret gun, which has been created by YouTube user kss5095 for his Advanced Mechatronics class at Penn State University.