Over the course of this month, Punished Props' Bill Doran is building a 1:1 scale replica of the alien assault rifle from District 9 to unveil with us at Comic-Con. Bill's build logs and videos will walk through his design and fabrication process, and his finished piece will be paired with a surprise at SDCC. Place your questions for Bill in the comments below!
In the previous part of this project, the molds we made were very simple. They were either one or two part box molds. The kinds you've seen Frank and Norm make in Tested videos. These types of molds made a lot of sense for the smaller pieces, but for the big body on the District 9 alien rifle, I decided to make a matrix mold.
I have never made a matrix mold before, but I've seen so many of my mold maker friends adopt this technique for most of their big molding projects. There are many benefits to going this route vs a standard box mold. The most apparent upside is a drastic decrease in the amount of silicone used. Silicone isn't cheap and, especially with such a large mold, you're can save hundreds of dollars by going the matrix mold route.
Diving into a new technique can be pretty scary, especially when it's such a large piece, but I didn't go into it alone. I had a ton of help from some of my mold maker friends. A huge thanks goes out to Thom from Sorenzo Props, Harrison from Volpin Props, and our friendly neighborhood Frank Ippolito!
A Note on Print Coats
For most of these molds, you'll see that I put down a "print coat" of Rebound 25 silicone before dumping in the Mold Star 15. It might be a little overkill, but I found that I was getting a bit of curing inhibition in the fine detail areas of other smaller molds using just the Mold Star. Not only did a brush on print coat of Rebound solve the problem, but it ensured that I captured all of the fine detail in the piece, perfectly and without trapping any bubbles.