Olight makes a special holiday set each year packed full of stuff at a very nice price. This year, they were generous enough to make two sets, one of which was the Transformers kit. It has the parts to make two different flashlights out of titanium, one single CR123 unit and another AA unit. There are caps to cap off the body that is not in use, so you could use it to house a battery while waiting to swap out the bodies.
Both lights have the same modes, with higher output when using the CR123 body and battery. The modes are two outputs and strobe, keeping the light simple without a ton of extra modes to muddle up the interface.
You already know what’s next. Here is a video showing the light inside and outside, in my backyard: