For some reason the Adafruit instructions on this confused me horribly, so for my memory rather than anything else, here’s a stripboard layout for the LM317. The input voltage should be at least 3v greater than the output voltage. There’s also an extra input protection diode and another capacitor slung in for good measure.
12v AC input gives +/- 12v DC outputs, just a bit less (11.94v or something). I added 1k resistors and LEDs between +12v and ground and -12v and ground as suggested in the thread (check Ken Stone’s power supply schematic for the exact details).
I was in a bit of a hurry and messed up first time round, if you’re going to build it, take a really good look at the diagram to see where everything goes, and what lines up with what. One downside of this layout is that it’ll be tight to add heatsinks to the regulators.