Making a LOTR or Narnia-esque Bow

[Icetigris]

I've been doing a bit of research on how they made the prop bows for Narnia and LOTR so I can make one sort of like it for a character I'm cosplaying from Fire Emblem. From the shreds of information I found, it sounds like they used a spring steel core encased in expanded polyurethane foam so they could dry-fire the bows without them breaking, among other reasons.

So my questions are: what type of polyurethane foam should I use? It seems obvious to me they used the self-skinning, flexible kind, but what density? How would I build a mould for this? How do you paint the stuff? Am I completely off base from the start here?

The character is Louise from Fire Emblem. Attached pictures are the bow and scheming I've done, respectively.

 

[Icetigris]

Here's the costume's shirt with the armour plates I've made.
Not really related to the bow, but have a picture anyway:

 

[BowstickArchery]

I know this is old.. but seems you got no help. If you want to revisit this, you may just think of using pvc pipe, and the foam insulation they sell. I wish i knew more about the moulds and foams to guide you in the right direction.

 

[RvanAken]

You could use pvc. There are some great toturials on YouTube. Just lookup the backyard bowyer

-R-