Cayth, Famed Mechanist

If a player or permanent has more than one kind of counter on it, and you choose for it to get additional counters, it must get one of each kind of counter it already has. You can't have it get just one kind of counter it already has and not the others.

Fabricate doesn't cause the creature with the ability to enter the battlefield with +1/+1 counters already on it. For example, Cayth, Famed Machinist will enter the battlefield as a 3/3 creature, then its fabricate ability goes on the stack. Players may take actions (such as casting instants) while the ability is waiting to resolve.

You choose whether to put a +1/+1 counter on the creature or create a Servo token as the fabricate ability is resolving. No player may take actions between the time you choose and the time that the counter is added or the token is created.