I’ve been to 39C3 and EH23. Here’s a photo of my badge, advertising something I shadily imported to Germany :)

witter.cz/@sebi@23.social/116374451432382202

There is a 12V-negotiating USB-C module (I had to mod it to support any of my powerbanks, and the only one is the size of the thing, twice as heavy and a fire risk (puffed-up 20Ah cell shoddily replaced with found 6x 18650), but on EH23 I was smart enough to get a long-enough cable to reach a pocket so my neck didn’t hurt.

The screwdriver, from a shitty Merkur-like construction toy set, is plus-shaped but not as sharp as Phillips and non-magnetic, making it easy to adjust the potentiometers (a Phillips would wear them out, and a flat one would be less convenient) without the display getting all wonky (even the magnetic field inside Hamburg S-Bahn trains from their power lines makes it wobble!)

The 3 kV is presumably only reachable via the thickly insulated wire between the flyback transformer and anode, however some high voltage does exist on the PCB between the CRT grids (for example, there’s about 48 volts between the brightness and contrast potentiometers). I used a piece of acrylic to cover the bare PCB but it fell off (shitty transparent tape) and I got shocked through my T-shirt. A little unpleasant but the current is low, especially after the small HV capacitor discharges, it felt like a normal static electricity fluffy clothing incident. I prepared the same piece of acrylic with holes for potentiometers for the front but it was matte, fell off even sooner, made it hard to adjust, and it was unlikely someone would reach inside so I abandoned it.