Where did you get the power transformer?

I work in construction and had a spare 40va transformer laying around.

It's a RIB 40va 120-24VAC transformer. Can be found on amazon. I suspect a 20va transformer would be just fine too based on how far I had to turn the dial down. It was hot enough at about 33%.

Why did you make that paper cutout?

I made the paper cutout so I could mark on the foam where I needed to cut. Originally I was going to leave the cutout pinned on the foam and use it as a guide but the hotknife easily cut through the cardstock I was using for the cutout.

Why do you store the bolt out of the gun?

I made a spot for the bolt because I wasn't sure how far it would stick into the top foam with the case closed. This way it sits deeper and is more protected. After seeing the knob on the scope and how high that sits, I probably could have left the bolt in the rifle and been fine. I wanted to make all the cuts I would ever need before it was glued down. I can always fill it back in with scraps if I choose to abandon it.

You glued the cutout piece of foam to the bottom piece?

This particular case had 3 layers of foam. The bottom, middle (which is where most of the cuts are made) and the top. I glued the bottom foam to the case, the middle to the bottom foam, and then the top to the top of the case.

I found this detailed guide on how to do this on an AR15 forum. https://www.ar15.com/forums/ar-15/Cutting_Gun_Case_Foam__lots_of_photos_/4-292695/