16 relays just arrived from China for use in the prototype:

I'll use these to make a single module:

controlled by the controller board I'm slowly bringing up.  Here's the MCU and associated passives (haven't had a chance to power it up and load any firmware into it yet):

With the prototype module I'll be able to test the controller board, relay sound, mechanical features, and even a two-node network (with another controller feeding commands to the module).  The 80/20 framing components should arrive Thursday.  Hopefully, I'll be able to validate the MCU by then and solder on the MOSFETS, RJ45 jacks, and RS485 controller (which Digikey just said Maxim is end-of-lifing; ugh).