Weapons Manufacturing is a rare Enchantment card from Edge of Eternities Promos (PEOE), collector number 168p. Current market price: $1.85 (foil $2.51), TCGplayer market prices via Scryfall.
Whenever a nontoken artifact you control enters, create a colorless artifact token named Munitions with "When this token leaves the battlefield, it deals 2 damage to any target."