Giving Modular creatures Persist to make them nearly immortal and growing them rapidly with the help of Birthing Pod. That's the main idea behind the deck.
Modular Machines
They cost quite some mana. The big ones listed further down cost even more, but we'll have the Faithful Four do something about that. It's definitely worth the effort. When creatures with modular die, their strength is transferred to a comrade. In this deck, we'll manage to have our cake and eat it too. Look:
Immortality rules!
Persist returns a dying creature to the field with a -1/-1 counter, which will cancel out with the +1/+1 counters from modular. That means persist will wor next time the creature dies, too. Creatures with modular 1 aren't useful in this deck, as they would immediately die again. Note that the returned creature won't have persist any more, so you'll have to refresh it with Cauldron Haze if it dies before Cauldron of Souls untaps.
Sacrifice Outlets
When death becomes meaningless, you can utilize it. By sacrificing an Arcbound creature, you can buff another, summon a bigger one from your deck and will get the sacrificed one back. By the way, isn't the artwork on Etherium Astrolabe incredible? I love that card...
Promoting to the High Ranks
C! M! C! 4, 5, 6, 7, 8... Weed will not get you there, but the Birthing Pod will. Work your way up the cmc ladder one by one.
Finally, the Faithful Four!
These are the cards I play in all my artifact decks. The upper two ramp, Fabricate improves consistency and Unwinding Clock is the artifact variant of vigilance, but also untaps the Cauldron of Souls so that your creatures will get another rebirth in the opponents turn.
Feedback is Welcome
If you know a way to improve this deck, let me know about it. If you find a particular weakness, reveal it. And if you like the deck, feel free to give that +1 button a good kick... ah, no, a click of course...