Summary

If you need to work on your EJ. Then you need this tool. It's a dang near perfect fit. When you twist it in, you'll get a satisfying click. It can withstand enough torque that I was able to break an adapter.
Do yourself a favor. When removing the camshaft gears. Don't even bother with the 10mm Allen wrench. Just get bolt extractors that allow for a socket to be used. Save yourself the headache and potential broken tools. You're going to replace the bolts anyway. If not, then at least the Allen will be ready for you to torque them to spec, lol.

Printed with PLA at 5-6 walls alternating with 80% infill (0.4mm nozzle). I wanted to make sure to give it the best chance before trying other materials. Luckily, that's all it needed :)

Subaru Intake Exhaust Cam Lock Tool.