Foundry Inspector

Artifact spells you cast cost {1} less to cast.

Shimmer Myr

Flash
You may cast artifact spells as though they had flash.

Raugrin Crystal

{T}: Add {U}, {R}, or {W}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Urtet, Remnant of Memnarch

Whenever you cast a Myr spell, create a 1/1 colorless Myr artifact creature token.
At the beginning of combat on your turn, untap each Myr you control.
{W}{U}{B}{R}{G}, {T}: Put three +1/+1 counters on each Myr you control. Activate only during your turn.

Parcel Myr

{2}, Sacrifice this creature: Draw a card.

Kappa Cannoneer

Improvise (Your artifacts can help cast this spell. Each artifact you tap after you're done activating mana abilities pays for {1}.)
Ward {4}
Whenever this creature or another artifact you control enters, put a +1/+1 counter on this creature. It can't be blocked this turn.

Myr Battlesphere

When this creature enters, create four 1/1 colorless Myr artifact creature tokens.
Whenever this creature attacks, you may tap X untapped Myr you control. If you do, this creature gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Cranial Ram

Living weapon (When this Equipment enters, create a 0/0 black Phyrexian Germ creature token, then attach this to it.)
Equipped creature gets +X/+1, where X is the number of artifacts you control.
Equip {2}

Brass Herald

As this creature enters, choose a creature type.
When this creature enters, reveal the top four cards of your library. Put all creature cards of the chosen type revealed this way into your hand and the rest on the bottom of your library in any order.
Creatures of the chosen type get +1/+1.