Here is an idea of a harware "firefly" that has three inputs and three outputs. Each output is controlled by the sum of opposite two inputs, and there is a threshold and a "build-up" followed by a release. This is controlled by on (or two?) speed knobs. The idea is to some extent to mimic a set of three very simple neurons with two inputs each.

This could obviously be simulated as a first step. I am thinking that a system of maybe five of these would be an interesting minimum.