Laser tripwire water balloon prank


Even though it’s a bit late for April Fool’s jokes, [Ameres] wrote in to share a project guaranteed to catch your friends (or enemies) by surprise.

Like us, he had some old CD-ROM drives sitting around and thought that there must be some way to put them to good use. He gutted one, saving the laser’s carrier unit for use as his mechanical trigger. He placed the unit above a doorway, soldered a pin on to the end of the laser carrier, and positioned a water balloon at the end of the CD-ROM’s rails. The laser carrier’s motor was then connected to a photocell located about half way down the side of the door.

He mounted a laser on the far side of the door, which is pointed at the photocell. Once the laser beam is broken, the CD-ROM motor is actuated, popping the balloon over the unsuspecting victim.

It’s not the most high-tech prank out there, but how high tech does a water prank need to be? We just wonder how easy it would be to attach one of these things to our cube at work…

Have any ideas as to how he can make a bigger splash with his friends?  Share them with us in the comments.

Water-blob launcher

This rifle-shaped water cannon looks great and packs a big punch. We guess you could say that it’s a water balloon launcher, but the balloons are torn off and drop like the wad from a shotgun shell when fired. So we think this launches water blobs, or orbs, or something along those lines.

[Wolf] built it using PVC and some brass fittings that allow for the injection of compressed air. There’s a slick valve system that he developed which we don’t get a great look at in the build pictures. Fortunately, there’s an animated GIF that shows the various stages. Using his valve there’s no need for any electrical system like a lot of other pneumatic launcher systems use.

Just like the water-filled ping-pong gun, you’ve got to be careful with this thing. As you can see in the clip after the break there’s lethal force behind these projectiles. Especially when [Wolf] swaps out the water balloons for big steel darts.

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