This is what I made out of the PowerSem modules I salvaged from the motor soft start controller.
The SCR is connected back to back making it analogous to a triac.
PCB was hand drawn due to it's simplicity and my general laziness.
MOC3020 triac output optocoupler drives the "big triacs" with mains AC. The LED input is driven from low voltage DC as one would expect.
I think the resistor in this one fits a 12V input but 3.3v shouldn't be an issue with another one. Fairly large AC loads could be switched on the output considering the power rating of these SCRs.