Activate Cogwork Assembler by paying ({7} magic symbol) , creating a token copy of Workhorse with haste that enters the battlefield with eight +1/+1 counters on it.
Activate the Workhorse token seven times by removing seven +1/+1 counters from it, adding seven ({C} magic symbol) .
Repeat.
Once you have infinite mana, you may instead copy any artifact you control.