at 5 INT, you can get better barter lv 3. The new, upgraded secret stashes seem (to me, at least) to be overflowing with crucibles...like 2-3 crucibles in each stock day.
Focusing on working stiffs stores and boxes will increase your chances of getting a crucible, as that's the kind of loot container that drops it.
Getting about 70k dukes and waiting 6 days will guarantee you to get a crucible:
Getting enough dukes to buy TWO fergettin elixirs means you can respec into intelligence, make however many crucibles you want, and respec back out.
Alternatively, salvage operations increases loot from wrenching, and there are numerous items that break down to steel. Safes, electrical and light pole-tops, and munitions boxes, to name a few.
You can buy steel from a trader as well.
High end quests will give Q5+ tier 3 items, like steel tools, augers, top end guns, top end armor, and top end weapons. meaning you don't have to craft them yourself, making steel unnecessary for anything except base fortification (which pretty much requires crucible for the sheer quantity you need) and building the top end vehicles.