Spartan Games Dindrenzi make for perfect AdMech ships.
Cruisers work for cruisers [duh], frigates for light cruisers, with a bit of 40k'ifying
Battleship is a bit too big, but I just hacked away middle section and it works way better now.
Some Wip's on my part: - Gothic and Endurance [When I'm done with those I can make some sort of tutorial on cheaply making various weapon sections for them.]
http://fc04.deviantart.net/fs70/f/2013/092/3/6/am_by_kharneth-d606vwb.jpgAquans, on the other hand, are good Eldar when you add 40k Dark Eldar Raider sails. Photos after I'll make some investments
Plus, Spartan Games Britannian ships, while unexpensive, make for great supply of Imperial prows if you're willing to hack them apart. I surely will be.