My seraphim have been converted using warhawk wings (the metal ones so I was able to bend them about). They ended up really top heavy so their bases are huge washers with extra sculpting putty. They take up a huge chunk of table... I sculpted the Cannonness' legs long long ago, and want to redo it now that I have learned more technique.
Here are the latest conversions. A new set of wing sculpts from scratch! That is GS over plasticard. I get better each time. Second comes my angel with a broken wing. Hey, the techs did there best to add bionic replacements, but its a dangerous job guarding a cannoness (yeah, the primer looks like crap, an old can. Oh well.). The last one is in progress, and needs work still. Standing, wings folded around her like a cloak.