heatsink
Mounted a few components in the case of ArduinoBox Serial# 2, including the heatsink for the solid-state relay. Should do the trick. This picture also shows the populated circuit board, which only had one small problem in that the terminal blocks on one side are too close to a set of female headers, so I had to replace the terminal blocks with female headers and turn the terminal blocks into a connector. Seems like it will work.
[singlepic id=6719 w=450]