Triggers for Coral Trap

I was wondering what type of trigger system do you use for a basic T post coral trap. I have the plywood and frame for it just need a trigger system that they can activate. This is an old school trap so any information would be helpful. I went ahead and purchased some paracord and the frame has the swivel for the cord to run though it.

I use a 2×4 to hold the door up. It's cut In half with a door hing holding it together. I'll run the rope from it to the back of the coral, roughly the 10 o'clock position.

Root stick

Rather than Paracord, I look on the net for some 3-6 mm Dyneema or Spectra cord. Like braided fishing line it has no stretch. Amazon usually has it.

I'll definitely have to get some of that for sure.