and7barton

Would it be feasible to have real fireflies ?

I make my own dry ice by squirting my big CO2 extinguisher into a canvas bag for a minute.

I'm looking forward to the digital version of this ! :-)

I've read articles to the effect in the newspapers. Often people have stuck a camera up, or a dummy camera. It invariably results in the police requesting that it's removed. The usual excuse is that it could be "a distraction to drivers".

A good project, except that here in the UK, the police would soon be knocking at your door and demanding you remove it. Only official speed detectors are permitted here.

I mould the sand / clay mix around the outside of a polystyrene (Styrofoam) cup, then allow to dry for a few days. When set, just run your propane torch around the inside to burn off the polystyrene. You get a nice smooth inner surface.

Actually it's YOU who seems clueless. You anneal copper by heating to a dull reddish black and QUENCH in cold water. The same process is used for brass and aluminium. To anneal steel, you heat and cool down as slowly as possible. With steel quenching hardens it. So annealing copper uses the exact opposite process that you'd use for annealing steel.