Check your game rules if you haven't already. Our producers have varying rules on trip wires and unattended/remote devices. I think one allows breakable wires.
I've often wanted to make an electronic skunk from a garage door safety beam. Set it to spray a mixture of paint and cheap cologne. Then there's no doubt who was hit. In our games though, I would just as likely catch someone on my own team.
Reffing near a red base one night, I started a blue player on an "hold" objective. I watched as another blue player strolled up and barrel tagged the first blue player and continued the hold. It was a bit cocked up, but I gave them credit for it.
What is fairly handy are ground planted motion sensor lights around the base at night. Harmless to your team, but lots of fun when the opposition steps into them.