This is the Hakko FX-901 portable soldering iron (available on Amazon: http://amzn.to/2sh7g0t). It runs off 4 AA batteries that you can swap out really fast with this removable cartridge design. I use rechargeables in mine and I get over an hour of use out of it before I notice the temperature drops. Alkaline batteries will run hotter, but not last as long.

I learned about the Robert Larson 800-2875 Plastic Center Finder (Amazon link) from maker Ben Light, who uses it to drill out the center in the tin can robots he builds. Online, I see a lot of videos of jewelry designers using these. Woodworkers use them on finding centers on dowels or centering up work to chuck into a lathe.