pogomonkeytutu

I've been given the task of turning a friends Longstrike into a Killzone replica for a Cosplay event in March.

I'm somewhat comfortable with taking it apart and putting it back together again. I'm also ok with the paint job it'll need.

By my question to all you budding Nerfers is what I can use as a lightweight material to make the extra parts of the gun that don't currently exist.

Here's the gun it's meant to be:



and as I am sure you all know, this is what it currently looks like:



As you can see, there's a lot more 'body' to it.

I'm based in the UK so I need suggestions of materials that I can easily get over here.

Any ideas of what I can 'stick' to it to make it match?