One potential downside of the project as designed was there was no way for the power to remain on longer than a half hour. For a soldering iron, a momentary interruption isn't a big deal, but I could envision other equipment you'd want to remain continuously powered while it's attended.

So the project now has a "warning" light in addition to the power light (which is just connected to the AC output power). The warning light is under software control only, and it turns on during the last 5 minutes of the half hour. If you push the button during the "warning" phase, then the timer is reset and the warning light turned out. As before, if the warning light is out and the button is pushed, the power is turned off.

This does raise a slight ambiguity in the user interface. The power button is no longer a simple push-on/push-off paradigm. The only way to preserve this paradigm would be to add the concept of a "long push" versus "short push." You'd push and hold the button for a quarter second or so to just reset the timer. A short push would turn the power on and off. The problem with this is that you then have to be cognizant of how long you push the button, and I think for this application that's a worse user experience.

Still, the behavior is simply defined by firmware. You can change the rules pretty easily.

The board design has been updated as well to use a smaller power supply module (unfortunately, it's not a whole lot cheaper), and incorporates the bleed resistor on the triac output and much thicker traces for the high current path.

I haven't built a new one, simply because the first one still works just fine. I will, however, retrofit it for the new "warn" light firmware and add a warning light.