Maker + stimulators?

Following up on the OP's question, can stimulators be used AFTER the forging process (Where you forge the weapon, grade it, etc), or does the stimulator have to be used right then and there?

If you can choose when you want to use a stim on something, it'd be cool to have Warriors/Buccs/Archers ask their Thief friends to help them stim their gear.

Right then and there. It's an optional ingredient that has to be included in the forging if you want to risk it.