If you have combat steel plates to 50. Then Superheat for while. At around 1,200 superheats an hour you get 60k+ magic and 30k+ smithing an hour. Not fast, but not bad and breaks pretty even on money.
Buy raw materials and make them into rings. Sapps at 700 ea, uncuts at 800 ea. Gold bars at 150 ea. Cosmics 100 ea. Sell for 1.5k - 1.8k. 500 ea ring, and good xp as well. Also works with emrald rings and ruby rings.
Addys Bars are better money, but Miths might be faster xp, at about 1.2k superheats an hour you get 36k smithing xp per hour. Just throwing that out there.
Steels buy 600 ea, sell 650 ea on forums. Very Easy to sell. Mith Bars buy 1.4 -1.5, sell at 1.6 - 1.7. Can be very difficult to sell. Addy Ores buy 1k ea, sell 1.2 - 1.3.