Anyway, Ratchet, Field Medic // Ratchet, Rescue Racer.
This guy has some pretty obvious lines of play - sac artifacts, gain life, recur artifacts. Implement of Improvement has never looked so good.
Beyond that card, though, things get a bit fuzzy. There are other artifacts that sac for lifegain (Sunbeam Spellbomb for example), but without any other bonus it's somewhat unimpressive.
So getting lifegain reliably requires more work. The simplest option I see is to use a lot of the typical lifegain package - Soul's Attendant for example - and just rely on your opponents giving you the fodder to recur your Mishra's Bauble or whatever. Notice that, since it enters tapped of Ratchet, we'll need a decent amount of fodder to pull this off at maximum efficiency, unless it doesn't require tapping as part of its cost (i.e. Elsewhere Flask).
I see Ratchet primarily as a value engine. Input lifegain and baubles, acquire card draw. Cool. So I think the difficult part is in finding a win condition. There are a few ways to go that I can see:
1) there's a lot of things that trigger on gaining life - i.e. Regna, the Redeemer. As long as we're already built for gaining life to trigger Ratchet, we might as well get some value off it.
2) there's also some pretty strong triggers off creatures specifically entering - stuff like Welcoming Vampire and Blessed Sanctuary. So we could include a bunch of the free artifact creatures, and then sac and recur them for value. This feels like it's gotta be either all-or-nothing. I doubt it's worth including the artifact creatures/sac outlets/creature etb effects unless we're going all the way in on it.
3) A different angle would be to focus on stax - since we don't need to cast many spells once our engine is going, and can generate plenty of value without even having creatures on board (since ratchet can be a non-creature artifact on enemy turns), we can make the board hostile to casting spells and controlling creatures without issue.
So that's where I'm at at the moment - there are a lot of baubles that can be used to generate value with Ratchet, but finding a good way to win I'm still not sure about.
Ah, mono-white problems.
edit: here's the list.
Ratchet
Approximate Total Cost: