What about CRTs?
Once upon a time, my college lecturer gave me an old Cossor 1032 scope. A panel on the side gave access to all the plates and the top scale went up to 500 volts per divison. Lets build an engine analyser first, perhaps I could get an ignition display of some sort on the screen. I wasn't going to be caught out by an electric shock- line a wooden peg with a bit of aluminium foil then clip it over the plug lead then connect that to the scope , that should give enough insulation. it didn't... The scope survived.