They'll be cast separately so they can be attached to the chest armor. That way I can still use the same molds that I'm using for Phasma. I've already made one version of them, but I'm thinking I'd like to re-do it if I can find better reference images.
For now I'm concentrating on the shoulders. As a few folks have pointed out, the TIE Pilot shoulder plates are different than the standard stormtrooper. They do look to be the same shape as the snowtrooper. So I guess that gives me two reasons to make them. While I do have a pretty decent digital model to work with, I also figure that the upper shape is close enough to the standard trooper that I should try to keep it consistent. With that in mind, I decided to modify one of my larger stormtrooper shoulder plates instead of starting over and having the robots carve out a completely new shape.
Here's how I stretched out the fiberglass parts:
First, I cut the bottom off of the shoulder plate, making a zig-zag cut in the straight section:
https://farm2.staticflickr.com/1702/24664323766_d7630a0225_c.jpg
Note that the vertical components of that zig-zag are all parallel. This will be important in order to keep everything aligned.
Since the pieces won't have much contact area to bond together, I added some tongue depressors to the inside:
https://farm2.staticflickr.com/1626/24063701103_8107cda5dd_c.jpg
Once I'd settled on how much length to add (a little under 2") I glued the tongue depressors in place:
https://farm2.staticflickr.com/1637/24572762592_8dbcfae39a_c.jpg
Here's what it looks like from the outside:
https://farm2.staticflickr.com/1632/24395018430_f376702b13_c.jpg
Since the tongue depressors aren't all that stiff, I needed to bond the pieces together with something more structural. This is where Bondo-glass comes in. This is a fiberglass reinforced body filler that's stronger (and heavier) than normal bondo:
https://farm2.staticflickr.com/1453/24063696683_04e205678d_c.jpg
Since the shape of the edges will need to be changed, I also added a strip of masking tape and built up some more bondo glass on these edges:
https://farm2.staticflickr.com/1665/24062362924_7ae8928e54_c.jpg
After the filler had cured, the tape could be removed to show the new edge:
https://farm2.staticflickr.com/1550/24690529495_9cd92e3500_c.jpg
I should mention that once the bondo glass has cured, it becomes structural. At this point, the tongue depressors could have been plucked out and the inside could be ground clean if I was going to make this into a wearable piece. Since I'm going to be pulling a new mold off of the modified shoulder, I didn't bother pulling them out.
At this point everything was looking pretty ugly and the bondo glass is very tough to shape once it completely hardens, so I did some rough shaping with a longboard and some 36-grit sandpaper:
https://farm2.staticflickr.com/1534/24597012211_ea5fdbba9e_c.jpg
Then I skimmed over the modified area with some normal Bondo in order to start the smoothing process:
https://farm2.staticflickr.com/1614/24572754942_457b119707_c.jpg
Once that firmed up, I did some rough shaping with a body rasp:
https://farm2.staticflickr.com/1663/24572754372_a250a8c5aa_c.jpg
Then shaped it a bit more with a sanding block and some 80-grit paper:
https://farm2.staticflickr.com/1650/24395009420_55bce561d4_c.jpg
Today I'll smooth it out a bit more, trim the edges to get the profile correct, and shine it up for molding.
I've also made quite a bit of progress on the TIE Pilot helmet, but all of the pictures look the same: spot putty, sanding, putty, sanding, putty, sanding, etc.
Hopefully I'll have it all glossy by the end of today.