[c0nsumer]

This is pretty neat, but is what you pictured the final product? It doesn't strike me as sufficiently robust for deployment. More like an engineering concept...

[nelop]

The final product is in a pi enclosure that is stackable, the two pi's live inside with the opto coupler installed inside.

It does the job, but the enclosures are plastic, they are tough, but I would preferred some machined aluminium.