Pet-Shield

Do you want your annoying pets to stay away from your room at night?

All you need is one of those staple-taker-outers that look like mouths, some fishing string/wire, 2 rubber bands, some kind of inch-long half-centimeter-wide tube, and some duct tape.

Wrap 1 rubber band around the staple-taker-outer loosely so that it isn't stuck shut. You need to be able to move it easily. It needs to want to shut though.

Now tape the staple-taker-outer sideways to the wall a few inches off the ground.

Now tie the rubber band around the tube as shown in the picture below.

Now put the tube in the teeth of the staple-taker-outer. Not all the way in, but just so the teeth are holding it. You should easily be able to pull it out.

Now tie the fishing wire to the rubber band tightly. Don't cut the fishing wire yet.

Now tape the other end of the fishing wire to the other side of the doorway. Cut the fishing wire. You should have what looks like a trip wire across the doorway. When your cat/dog tries to walk into your room, they will trip on the wire, sending the tube out of the staple-taker-outer's mouth. The tube will gently strike your pet's side. Your pet will be stunned and run out of your room. If the tube doesn't launch out of the staple-taker-outer's mouth, tighten your fishing wire, and try it again.