MK I, Scrap Suit

Equipped creature gets +1/+1.
At the beginning of your end step, put a shield
counter on equipped creature.
Upgrade — At the beginning of the end step, you
may sacrifice this artifact. If you do, search your
library for an Equipment card with converted
mana cost equal to 1 plus this artifact's converted
mana cost, put it onto the battlefield, and attach
it to a creature you control, then shuffle.