The rat trap claymores I made weren't tandem. They were one trap, with the cloth pouch folded under the arm. Clever placement of a few eye hooks allowed the trip wire to be strung comfortably around, and same eye hooks also were used to "stake" the trap into the ground.
Mouse traps, while not powerful enough to throw BBs can be used as an alarm device. The "alarm" I used was four cap-gun caps. As you are looking down on the mouse trap, where the arm is designed to strike the rodent, nail through it four small headed nails at equal levels. Place your caps on top of that, and secure with a loose tape. Run your wires, arm the device, step away slowly. It makes a good noise, alerting you, your stalker, your spotter, and other friendlies in the area that some one has tripped your alarm.
To further add to the fun, I have been known to throw out bait in a nice open area. Such bait includes dead springer pistols painted black, dead/shells of M4 mags, bottles of BB's (stuff I swept up from the range and staging area where we play), and whatever irrecoverable detritus of the airsoft world I can get my hands on. Usually, a player will stop, look down for a few seconds, or crouch to examine if its a) worth keeping b) worth turning in to lost and found. In either case, they stopped to bent over and take a peek see, meaning its a much easier shot.