Apologies for the slow updates. I settled on a machine to take forward and have been making awkward, halting forays into it.
I chose #67 because it seemed to offer the most possibilities while still being a fairly concrete shape. It was actually a thing with a purpose rather than an abstract shape, which makes my job infinitely easier. I started by just playing with the shape, squashing it and looking at it from various angles.
More playing with shapes - at this point I'm still not sure if it's a spaceship, an airship, a submarine or a common-or-garden ship, but by the end of this spread I've decided on it being spacefaring. I looked at ways the wings could move, up-and-down like a jellyfish or back-and-forth like a rowboat.
Taking the jellyfish idea further - the wings would be completely inefficient in a vacuum, so maybe they're for use in hyperspace. Physics can't tell me what to do when I play the hyperspace card. Also looking at ways the wings would move and rotate - the rotate-y thingy which I'm sure has a technical name would allow the ship to move at almost any angle, and would probably also come into play when braking. I also tried adding some tentacle things with guns on the ends (full movement on every axis would be handy) but it just looked like I was trying too hard, and I'm still fond of it being a cruise vessel rather than a warship.
Still negotiating with the shape - I finally settled on a setup for the 'wings', making them a single piece in a sort of crest. None of these shapes seem right to me, but the more pointed nose seems better in profile than the simple half-sphere. I also feel the exhausts in the back are clunky, but my brain won't let me get rid of them because doing so would leave it with a very inefficient way of creating thrust. God dammit, physics, why do you do this to me?
More silhouette wrestling - I added a very Warhammer 40,000-ish prow for a giggle and to see if it would get anything moving. It sort of did, I like the second shape that came from it, but I'm still not happy with it. I feel like it's getting closer to what I want it to be though, which is a start.