Liberator, Urza's Battlethopter is your early'ish creature. It let's use cast most our cards as though they had flash. Which opens up some bait tactics when leaving open mana on their turn. Also it will only get bigger the more cards we play.
Cloudsteel Kirin is an early'ish creature to chump block with. It can be equipped later for to any other creature including those massive Constructs and it gives them some evasion with Flying but also makes it so you cannot lose the game unless they remove it from play first. This is pretty huge because at the point you get this attached to something you might've taken some hits to your life and need this to come online.
It also doesn't matter whether you go under 0 or less life, you're forced to draw a card while your library is empty, you have ten or more poison counters, you're at the end of your Nine Lives, your opponent is a Triskaidekaphile, or so on you just keep playing. Also whilst attached as an Equipment it ceases to be a creature so it also loses any creature subtypes it has — Kirin. This isn't that important other than it also means they cannot target it as a creature, so if the creature it was attached to had hexproof lets say for example they would need a destroy or exile target artifact/equipment and not simply a destroy/exile target creature card. This is just hypothetical situation but still worth pointing out.
Brass Knuckles is a really nice Artifact because it puts out not one but two artifacts that have a cost of . Each enterring the battlefield would trigger the Simulacrum Synthesizer to make not one but two Construct(s). Then you can equip them both for just to either the same creature in order to give it doublestrike OR better yet if you have two creatures and say Cloudsteel Kirin, Blade of Shared Souls, or Assimilation Aegis equipped to them then you would equip each of the Brass Knuckles to separate creatures in order to give them BOTH doublestrike. Ideally you're going to want to equip your Construct(s).
Assimilation Aegis is removal. It's an artifact but it's main usecase for us is a much needed answer to their threats. The deck should have a decently strong board presence with Constructs to deter any would-be attackers but removal in artifact form could be useful for those pesky threats who need answering. If this card underperforms though you can easily swap it out for something else. Generally the threat you need to remove is worth having the removal though and if that threat is that worth it you might even equip it to something else to morph it into their threat and steal it for yourself! A simulacrum if you will. Pretty thematic.
Encroaching Mycosynth is a really cool card for artifact synergies. While we only have a few non-artifact non-land cards in this deck it does make Mondrak, Glory Dominus and Ojer Taq, Deepest Foundation
artifacts which then makes them targetable by the next few cards as well as triggering the Synthesizer.
Transmutation Font as the top end of your curve is a nice payoff because you can tutor out any artifact you're missing and put it onto the battlefield which of course triggers Simulacrum Synthesizer to make a Construct(s) too. If you don't wish to sacrifice a Construct just tap it to create three different artifact tokens to get the tutor effect.
Chimil, the Inner Sun is a nice curve topping artifact. At your endstep every turn it's cheating out basically any permament for free with the choice of putting it in your hand if you'd like. Your hoping to hit an artifact of course to trigger the Synthesizer and creating an untapped Construct. Chimil is also just great that your cards you cast cannot be countered. We probably run only one of these because of the high mana cost and due to the fact that we will lose Mirror Box eventually and it is Legendary.