Actually came here to suggest Stabbity's Crescent Rose scythe tutorial but it looks like she's got that covered!
As for the expanding foam, cover it in a layer, maybe two, of paper mache, then a layer of paper clay, and then sand it down to the right surface texture if there are any unsightly bumps. You can then paint over the paper clay!
Sac-Anime Winter 2014
Friday: Mikasa Ackerman (Attack on Titan)
Saturday: Yang Xiao Long (RWBY)
Sunday: Rikku (Final Fantasy X-2)
Mitsuki Nase (Kyoukai no Kanata) (10%)
Liz (Soul Eater) (planning)
Medusa (Soul Eater) (planning)
Crystal Pony Rarity (MLP:FiM) (25%)
Homura Akemi (Puella Magi Madoka Magica) (10%)
You can call me Meg.
I like RoosterTeeth, indie music and poetry, and American Spirit menthols.