Gravity UP, give more Transformers.
But seriously...the only real machines in the game right now are Armagio and Steam Machine, both of which have high HP and low attack. Therefore I think the standard machine built either as a ramp or slow damage should follow this trend.
Note that thematically, Steam Machine is a very solid card. It's a machine (duh) that contains water; you give it heat (fire) and it produces steam, which is used for energy storage, and this is transferred immediately into powering the machine (attack boost), and the steam gradually disperses, lowering the energy (attack loss). Why can't Arctic Squid have this kind of thematic balance?
*cough* Anyways, yeah. Machines are very fun and somewhat simple to design, as one can place them in the future where we have things we do not currently have. Of course this can only be stretched to a certain point, so no Svruncatillax for us.
Here's some theory on a hovercraft.
What do we make it out of and what does it contain? Then, what element can we put it into? Personally my dream hovercraft would be built like a flying saucer, with the top half made up of reinforced plastic or glass for viewing, and the bottom made of a solid and flexible metallic alloy.
Obviously a hovercraft travels through air, so the card should have airborne. Maybe instead of a human's hovercraft, we make it a stereotypical Flying Saucer, and we give it a beam. Maybe the beam teleports a creature back to it's owner's hand. Maybe it steals a creature.