If the idea were a painless "clean looking" death, then a tank of nitrogen, a rubber tube, and a mask are all that you would need. Painless, cheap, effective,

If the idea were a painless "clean looking" death, then a tank of nitrogen, a rubber tube, and a mask are all that you would need. Painless, cheap, effective, and could be administered by anybody so you don't need a nurse to insert the needle. You could pull the nitrogen straight from the air at the facility so you wouldn't even have chemical supply issues (not that local welding gas supply companies would face international pressure to refuse shipments anyway...) That executions are not done that way is all the proof that I need to say that executions are not currently designed to be painless. They are designed to appear clean, but specifically designed to torture.