Activate Shilgengar by sacrificing Weaponcraft Enthusiast.
When Weaponcraft Enthusiast dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
When Weaponcraft Enthusiast enters, its fabricate ability triggers, putting a +1/+1 counter on it.
Resolve the Shilgengar ability.
Repeat.
This intricate loop relies on Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight functioning on its Isilu side to grant your other nontoken creatures persist, allowing Weaponcraft Enthusiast to continually shrug off death. When you feed Weaponcraft Enthusiast to Shilgengar, Sire of Famine's sacrifice ability to churn out Blood tokens, the persist trigger brings the Enthusiast right back, where its fabricate ability immediately drops a +1/+1 counter to neutralize the incoming -1/-1 counter through state-based actions. This resets the cycle entirely, letting you endlessly sacrifice and resurrect your crew to fuel infinite artifact tokens and death triggers.