Thanks again guys!
As promised, here is a quick tutorial of how I work my EVA. I did my best not to miss any part, but if I did, or you have further questions, feel free to ask.
First, the two (four if you count both sides) parts I worked on. I highlighted the peaks in orange and the valleys in blue.
Next, I draw the parts onto cardstock. If this is my first piece, then I perform many measurements to obtain the design. However, these are built off of the plate above, so I used that piece's cardstock template as my base. I then freehand the rest of the part, using my body and common sense as reference. I then draw in where the peaks and valleys will be.
I then transfer the cardstock templates onto EVA foam
Next, I cut ONE piece at a time, and draw in the valley or peak that was created by that cut-out. I only do one at a time to make sure that the baselines are always the same. If not, I run a high chance of the pieces being off by as much as 1/4". This equals a lot when doing the forming.
This part shows after my cuts on the backside. As you can see in the photo, I decided to add in two valleys in the top piece to help with that curve that is needed. Also, I find it easier to put down my scalpel and use a single edge box-cutter style blade to make these cuts. A bit harder on the hands, but I get a better feel for the angle and depth with these.
Here is where I do a test forming without heat to make sure that all of the angles are correct. If not, I will usually end up cutting a bit deeper or wider to compensate.
Another thing I will do is make sure everything still lines up to my original piece. I know how much they will "shrink" now because of the new angles created in the forming process.
Then, with my heat gun on LOW, I take time to make sure that both sides are very warm. I want them to be easily bendable, but not so much as to melt the EVA. Here is each of the pieces after the initial forming process is done.
Next, I take my glue gun and fill the recesses where the peaks are. This gives me an even sharper and more consistent peak. To make sure it holds it's place, I immediately run it under cold water to solidify the glue.
Final fitting... yep, I think these will pass
Hope this helps