We have all been there. It's October and the only thing standing between you and an unbelievable Halloween costume is the fact that you are not a professional makeup artist. For me, the only thing that I needed was the ability to make an amazing looking mask that fit perfectly to my face. Traditionally, these sorts of accessories are made by creating a cast of your face, sculpting a form-fitting mask on the copy of your face, then creating a mold of the appliance, then casting the prosthetic! I had the ability to do precisely NONE of these steps, of course I couldn't make the mask I wanted... or could I?
Being one to happily push the capabilities of both software and my own creativity, I wondered if there was a way I could create this mask with SketchUp.
First, I needed a positive of my face: a 3D stand-in for my face that I could model off of. A while back, I had my face scanned for a 3D print. Seemed like I could do that again! Fortunately, the Structure Scanner took about a minute to scan my face and give me a great-looking mesh that I could import into SketchUp! Importing the STL file only took a few seconds. Then, all I did was group the geometry and run Soften/Smooth (purely for aesthetic reasons).
Next, I needed a rough outline of the mask on my face. To do this, I aligned my parallel perspective camera straight-on to my face and placed a reference plane (just a plain old rectangle) in front of the camera. Since I wanted to see through the rectangle, I filled it with a 50% transparent white material. Why not simply turn on X-Ray? I wanted to be able to see through the material, but not snap through it. The transparent material forced me to stay "in plane."
From here, I drew a basic outline of the mask shape I wanted. My plan was to use SubD to smooth out the final mask lines. At this point, I made sure that the model I drew to create the outline was made of quads (a secret "3D modeling nerd" term that means the model faces are made of four-sided shapes).
Ed. note: Aaron also used component mirroring to model and maintain symmetry for his mask.
Once the outline looked good, I used Push/Pull to extend the shape of the mask through the face scan. Since the model of the mask would eventually be intersected with the scan geometry, it was important that the mask geometry pass all the way through the head. Fortunately, pushing objects through a human skull is far easier in SketchUp than it is in the real world...
Once the outline looked good, it was time to start sculpting! I used Vertex Tools to shape the front face of my mask. I could have used SketchUp's native Move tool, but Vertex Tools assured that the quads were maintained. This was probably the most time-consuming step, but also the most important, as it established the character of the mask.
Once I completed the rough shape, I smoothed my mask geometry using SubD. This was actually a back-and-forth process combining Vertex Tools, SubD, and the Crease Tools (in the SubD toolset). As the geometry comes together, some surfaces run back, through the face scan. This is just fine, because...
Next, I needed to intersect the geometry of the mask with the geometry of the face scan. This was a pretty simple case of Intersect with Model. After that, all of the extra geometry was deleted.
After grouping the mask geometry, I ran Solid Inspector2 to make sure that the mask was printable. While it was not a major effort, there were a few gaps in the model that had to be patched before it was a printable solid, and ultimately a 3D-print-ready STL file.
Of course, I would have a hard time wearing an STL file on my face. To make it "real," I opened the STL file in FormLabs's PreForm software. I positioned the mask so that the section that would be against my face was turned away from the build plate. This meant all of the support material would be generated on the outside of the mask: important as I could always smooth out the outside of the mask, but I wanted the inside to match my face scan as precisely as possible.
Then it was off to the Form2 to make this digital dream a reality! While I could have printed this on any of the 3D printers in the office, I wanted the back of the mask to be as precise as possible. While the "fine" settings on the FDM printers are great, it's hard to beat the precision of an SLA printer!
Once printed, the mask looked great. (I resisted my urge to push it up against my face until AFTER the excess resin was removed). It fit perfectly, but the removal of the support materials did leave some scratches on the front of the mask. Fortunately, the resin used in the Form2 is sandable and paintable! A little 400 grit sandpaper and the marks from the support were gone. Unlike sanding a print made from ABS or PLA, sanding FormLabs's resin was very similar to sanding wood. It was pretty easy to take the imperfections down.
But unfortunately, the marks from the sandpaper were very easy to see. Good thing there is a solution for that, too! Wet-sanding helped to polish up the mask until it looked perfect! Overall, I was really impressed with how easy it was to work with the Form2 Resin.
I was honestly surprised at how well the final mask turned out. It looked like a molded prop and, thanks to the initial scan data, it fit absolutely perfectly onto my face. Now all I have to do is put together the rest of my costume... too bad I can't use SketchUp to make clothing! Or can I?