Arsenal Thresher: A fantastic hard-hitter, which can turn dead draws and bad starts into explosive mid-game plays; the more artifacts you have stuck in your hand, the bigger it grows!
Ashnod's Altar: The key part of the deck; this activates the infinite combo, and can somewhat help with ramp, and using Workshop Assistant to fish up other artifacts when needed.
Barren Moor: Seems an appropriate one-of, allows for less dead draws.
Brainstorm: Allows some good sifting and sorting of the deck.
Cast Down: As a dimir deck, it would silly not to take advantage of very powerful removal spells.
Dimir Aqueduct: Allows you to occasionally return an artifact land to your hand, which Arsenal Thresher and Glaze Fiend are grateful for.
Etherium Sculptor: A key piece for boosting your earlier turns.
Faerie Mechanist: Is pretty handy - allows you to fill up your hand in the late game, and sits around long enough to feed Arsenal Thresher as a bonus.
Glaze Fiend: Is an alternative to Disciple of the Vault when necessary, pumping infinitely and flying in often unblocked. Can also swing for a surprising amount of damage on ordinary turns, when you consider the artifact lands.
Halimar Depths: Can be useful at any point in the game for sorting cards, pairing well with self-mill cards.
Lonely Sandbar: Again, allowing less dead hands.
Mortician Beetle: Turns your infinite combo into damage.
Perplex: Is a nifty counter, as well as a tutor for Ashnod's Altar.
Ransack the Lab: Is important for putting Workshop Assistant into the 'yard, and pairs well with Reconstruction when storing cards for fishing out later.
Reconstruction: With a deck that self-mills, this sort of option is great for comebacks and accidental key piece mill and such.
Seat of the Synod: Incredibly helpful, all sorts of synergies.
Thought Scour: Allows some minor mill and draw.
Vault of Whispers: Again, bloody useful.
Witching Well: Is pretty nice for artifact synergies, and draws decently in the late game.
Myr Retriever: The final key piece; cycles infinitely if you have another in the 'yard.
