Working on the same project!! Was now looking for some info to start the software... but the hardware is already done, and have some ideas to share... i'll try to take some pics, but what i've already done is this:
for the arming, the team has a set of 3 db9 terminals that has to insert on 3 db9 plugs in the right configuration, that to power up the bomb and get it ready to arm.
To disarm, i have two metal cilinders, one with a plastic tube inside and metal bottom, and other with a plastic cup on the bottom. On the top of the one that has the cup is a plastic cap with a metal pendat connected to a relay. what the player has to do to disarm it is remove the cap from one tube carefuly so the pendant doesn't touch the metal walls, and then insert it in the other tube. when the pendant meets the metal bottom of the tube it will disarm the bomb...
hope you undestand 