When crafting, keep an eye out on the craft menu, where choice like standard synth, rapid synth, etc. are. It will be under the option to wait. Same goes for the others such as tender touch, masterpiece, etc.
I'm not quite sure what the conditions for it to show up are, but it seems to appear pretty commonly. You might want to play around with it for a bit to get a feel for it. I'm pretty sure you can use multiple crafts abilities on any craft, but you are limited by the amount you can hold on your actions and traits list.
To expand slightly on this: once you set it in your actions and traits menu it appears randomly under wait when you are crafting but the box size never changes, meaning you should see a scrollbar appear on the left hand side when one of them appears.
From my limited use so far once you use the ability it will not appear again for that synth attempt, though maker's muse seems to last 3-4 actions worth before fading again. if you do not use the ability when it appears however it may or may not show up further in the synth attempt