FYI: There are three wires used in a 120Vac AC Circuit such as you would control. Ground, Neutral, and Hot (Power).

The color coding for the connecting wires is Green, White and Black. (In a 220VAC Circuit, power is also supplied via a Red wire and, often the Neutral is not present,

While the Neutral and Ground and not described as "Hot," neither is described as 'Cold.' If you were, indeed wiring all the SILVER connections together, these would be the Neutral connections and should be connected (joined, linked, etc) with a White insulated wire.

If you check the power cord you used, you may find there is a color-coded wire insulation for each of the three wires. On some power cords, one of the connectors is 'ribbed' linearly to define the Neutral conductor (or is it the Hot connector - got a meter handy?).

All in all an ambitious project and worth saving for future reference. I was impressed by the cover plate you made as well.