irekon..no, I'm retired now... probably a half hitch was not the correct term...fold a loop back on itself, and put both resulting loops around the knob as a slip knot... I had a hallway entrance to my lab room from one hallway, and a counter top at the edge of the other door with which to lean the 2x2s as jiggling the door would allow a short horizontal block to slip off the door frame... the doors were locked from the inside but accessable by anyone with a master key...probably a better solution would be to use a piece of chain and bolt through the links..what I used was in response to a "what if...." one afternoon, and I used some para cord and meter sticks... the sticks slipped so I purchased the longer 2x2s

a slotted 500g mass can be driven onto a meter stick to make a pretty good trunchon

I helped review my school's emergency management document after the Columbine attack... as the shooter on the faculty my Principal asked me to be on it... I played the role of devil's advocate, especially with improvised explosives and firearms...