BARF..... BARRRRRRFFFFFFFFFF!!!! xD Good times, great movie!
In the costuming world you can never actually bark up the wrong tree, some trees are more bark-up-able than others is all
If you have plan in place, and have done your research then 99% of time your idea will achieve realisation.
Personally, I would start with a headband - A flat one prerrably with a metal rod in the centre, not vital though. From there, adding a strip of styrene which follows the curve of the head around the back (more or less ear to ear, much like a respirator holder. From there, at strips going from the back piece up to the headband to give little platforms.
After that, make the basic shapes of the ears from anything you can attach to the headband (I would leave a lip at the bottom of the ear, so i could put 2 tiny bolts up through it (2 bolts per ear to ensure it stays in position) to hold the ears in shape.
After that, attach pieces of a cut up wig on the platforms and blend them together neatly, and use hair spray to get the partial combed look he has going on.
____
THats just what I would
Your way would work just as well!
In terms of foam, all you need are welding gloves(for safety if you want to prevent burning yourself) , a heat gun, and solid non flammable shapes to press the armor into whilst heating.
This video should take care of it :
Heatgun Foam Armor Tutorial - YouTube
