I made a series of three costumes from Mad Max: Fury Road including Immortan Joe, Furiosa and Nux. For Immortan Joe, I focused on the mask. While it's definitely not an exact replica, it worked pretty well for the costume.
Step 1: Bondo Up That Mask
I started with an old 3M respirator that I'd had for 10+ years and removed the filters and took off the straps that go around the head. I kept those around and later attached them to the leather straps with elastic so I could adjust the mask on my friend's head.
I used the Bondo to build out areas of the mask to give it more body and remove the angular edges. It also is a drillable surface which came in handy when attaching all the pieces and parts. The pictures show the first out of three or so layers I did so it got pretty thick in the end.
A note on Bondo: I've worked with epoxies and resins before, but never with Bondo, and probably won't again. It was difficult to control and had about a 30 second window between slumping and curing. I have a newer respirator that I wore and had the studio well ventilated but the smell was still pretty intense for a couple hours after so I kept my mask on most of the evening. I know some people swear by the stuff, but I'll go with another method next time. And like all industrial sculpture supplies - wear a respirator, work in a well ventilated area, wear gloves and read up on it before using it.
Step 2: Teeth
After the mask was built out, I sculpted the teeth out of Sculpy and baked them. I left them in for 10 minutes, which was a little long for how thin they were and they burned black. It's the first time I've ever had Sculpy turn black on me. One of the down sides of wearing a respirator is that you can't smell when something is burning. So now I have a good lesson on that.
Step 3: Paint
Since I turned the teeth black, I didn't need to do an undercoat, but it did make it tricky to get the teeth color. I did a few coats of acrylic on the teeth to get that nice horse yellow look.
Step 4: Gaskets
So I ended up using two types of gaskets and connectors, mostly for the look, but it also ended up being useful for attaching the tubes. This was the first set of rubber something or anothers from the hardware store that looked about right.
Step 5: Leather Strap
To attach the leather straps, I drilled through the mask and used book screws to attach it all together, it was a strong hold and was easy to take on and off when I needed to make adjustments. My new favorite thing ever are book screws (sometimes called binding posts). I used tons of them on my Furiosa costume.
Step 6: Finishing Up
With the major bits together, I added straps, painted and detailed out the rest of the mask. I used the adjustable strap from the original respirator with some fresh elastic and waxed canvas. The vacuum hose was given a quick whitewash to look dusty and fixed in place with wire. I added that to a blond wig and boom. Joe. In the flesh.