In this Instructable I wll be showing you how to make a Mousetrap Mine using a tripwire. This little beauty flings a bunch of airsoft pellets or other small article at high velocity toward your hapless victim (that'll teach your little brother to stay out of your room!). This version is more reliable than previous ones becuase the tripwire releases the retaining rod directly from the holiding tab, instead of just jiggling the release tab.

This project requires:
- Cheap mousetrap
- Masking tape
- Thin string or thread (you can also use stero wire without the insulation to make it stronger)
- Scissors
- Stapler
- Paper clip
- Pliers
- Small screwdriver

Step 1: Staple the Back

Take a cheap mousetrap and staple four times into the back of it so you can attach the string to something. Staple the two horizontal staples first, then the verticle ones. A more powerful stapler will help here, but since I only used a regular one, four staples are required. Take a small screwdriver and pry the two horizontal staples up a bit, as shown in the picture. At first, I tried to attach the string to the little U-shaped piece of metal that supports the release rod, but after a few launches it pulled it right out.

Step 2: String Up the Lever

Cut a piece of string about 1 meter long. Slip it under both horizontal staples and tie it securely. Trim the loose end. Then wrap the string around the metal bar that kills the mouse. Wrap it around twice, then go back to the staple and wrap it around the one that's closest to the edge. Then go back to the metal bar and wrap it around again. Then wrap the string around the staples alternating which one you wrap it on. This spreads the load around so it's not all on just one staple. When you get the the end of the string tie it to whatever's closest, the bar or the staple.

Step 3: Make the Payload Holder

The payload holder is made from masking tape. It took two strips of masking tape to get the "base" of the payload bay. Then take a piece of tape start making the walls. Tape a piece to the front, and then fold it over, leaving a lip about 1 cm long. Do this to the top and bottom. Then do it to the other side and the top. The bottom is a little trickier. I had to cut a bit of tape away so I could get the other tape through. Stick the tape, sticky side up, through the little gap and then secure it from the back. Then fold it over and repeat. When you're done all four sides, take a small piece of tape about the size of the overhang and bend the edges up and tape them to each other to form a sort of box. Do this to the outside and inside of the box.

Step 4: Make the Release Mechanism

This release mechanism uses a paper clip to ensure positive release of the rod. Unbend a paper clip as shown in the pictures. Note that I used a large paper clip, so if you use a small one, you may have to unbend another part of it. Bend the paper clip so that the unbent part is perpendicular to the bent part. Then tape the clip to the bottom of the mousetrap so that the clip sticks up about in line with where the rod meets the retainer. See picture. Use the pliers to bend the clip to make an eyelet for the tripwire to pass though.

Step 5: Make the Tripwire

Tie a knot in the tripwire with a loop. Cut off the excess. Pass the loop though the eyelet of the paper clip. Then slip the rod through the loop in the tripwire.

Step 6: Notch Out the Payload Bay

Fit the rod into it's place and note where it presses down on the walls of the payload bay. Then take a scissor and cut some notches for the rod to fit in.

Step 7: Finishing Touches

Tape the contraption down where you want it. To test the launch, slip the tripwire onto the rod and put the rod into the keeper. Then, give the string a little jerk. The rod gets pulled out of the keeper, which releases the payload bay, and one (or more) projectiles are on their way downrange. Another thing you can do is tape the strings together with very small pieces of tape so the string won't get spread out after a couple launches. Attach the tripwire to a door or just position it in a place where someone will walk into it, and you're ready to reak havoc on your unsuspecting targets!