Simultaneous electronic shutter release for multiple Lumix G7 cameras
ordinary mechanical relays are fast enough to manage 1/1000 second accuracy

have one set of relay cntacts and one set of resistors for each camera. (or two contacts if you needs focus and shutter)

solid-state relays can be non-ideal in interesting ways, but the right one could work too,

or you could do it in discrete transistors like this;







simulate this circuit &ndash; Schematic created using CircuitLab

(immagine that repeating bit four more times)