I volunteer as the fan inside your suit.
So I guess the furmeet yesterday inspired you? :P

no i have been obsessed for months now

All I know is that suit would have the best footpaws...

YES

You've gotta show them off to all us paw sluts! <3

I worked on a fursuit head myself D: If you put in a fan, make sure that you actually have vents for the air to circulate inside the head. I think the ears are the best spot for that, or maybe the eyes but don't quote me there. All I know is, the head I made is bulky--I glued a fan into the snout and put in nose slits, but the fan doesn't actually do any cooling or provide actual air (Maybe it's just hard for it to get air through the nose, I'm not sure).

But definitely make sure that you are getting air while wearing the head. Also if you do use foam, be cautious about using sharpies to mark stuff, because it might bleed over on your face later when you sweat.

What sort of elastic material are you thinking of?

Either way, it'll get hot regardless if you have a fan. It's dependent on your own heat tolerance and how much you sweat.

I strongly suggest going though the tutorials here on Matrices' site if you haven't seen it.

http://www.matrices.net/tutorials.htm

I've been a suiter for about a decade at this point, I've made one suit and have assisted in the construction of many more.

I've made them..yes a small fan or two blowing outward helps, but you need an intake vent so there's a path for air to move. Unsure what you mean by elastic interior?

Ive made two! In my experience the MOST important thing is, how is the mouth/nose ventilation? If you make a head with a mouth that is fairly big or opens wide your nose and mouth will thank you, circulation doesn't really make a difference everywhere else except for comfort (No bits poking through or friction where your face is) A fan is usually needed if your making a head that doesn't have a big ol mouth that can open/is open or if its made of that very hard plastic material. This is my experience atleast