So firstly Pact of Tome allows you to take any class's can trips. You don't need to limit it just to warlock cantrips.
Guidance is probably the strongest utility choice although it depends how much tolerance your DM has for you Guidance-ing everything.
Shape water and mold earth are also really good fun and occasionally helpful.
Minor illusion also has a ton of uses, but I'm not sure it can be used to forge anything? It won't withstand being touched.
You might want a damage cantrip which uses a saving throw (in case of high AC enemies) and you can't go wrong with Toll the Dead.