Merchanting cballs won't help him get smithing levels. Cannonballs are incredibly slow and crappy smithing exp. And selling them can really suck sometimes. If it's profits you're looking for, do the blast furnace. The fastest way to make mucho profits there is with steel plates. Start by world hopping to put 250 coal in the furnace. Then solo there, buying iron from the ore seller and smelting/smithing/alching steel plates. You'll make money and some good smithing exp. A good alternative is to buy addy ores and then mine coal, superheat addy bars, and then make arrows. Sell for 150ea, and you'll make a nice profit. 1k addy ores will cost, at most, 1 mil, and after the cost of nats and arrow shafts, you'll still come out, at the very least, 600k ahead. The best thing about the second method is you get a lot of mining exp as well. And if you have 85 mining, do your superheating in heros guild to pick up some rune ores at the same time.