Until something more permanent can be installed, perhaps the only fool-proof solution is to seal the cockpit completely from the cabin with a three-inch thick hardened metal wall aft of L/R 1. Then it wouldn’t matter what happened in the cabin, the only way to access the cockpit would be on the ground via a separate entry door. No guns required, stun or otherwise.
I was just out looking at buckets, Devil, and some of them come in very eye-pleasing colours. (I even saw one with a bulls-eye painted on the inside bottom.) You just have to go easy on the hotter curries the night before.