For building new comb, sugar water can be used. Hive temp at comb building location needs to be in the high 90's F. They will cluster and build up the heat they need. Use an entrance reducer. Wads of grass can work, or whatever. It doesn't have to be a custom made (and commercially sold) reducer.
But to build up brood, they must have a protein source. I don't care much for the soy powders, but they are commonly enough used as an ingredient in supplements. There are different supplements on the market. I won't try to steer anyone to certain products. If there is a University Library nearby, see if they have any Bee keeping magazines? there were some articles in the last year or so --- but I can't recall which mag.
Water too is important at all times, specially in summer.
Good luck. If you have enough flowering trees around, they may build up well enough with no suppliment. Mixed wildflower is usually very good. Not all pollens are equal, though. Some lack enough protein. An example being comparison of blueberries (not nearly enough) to blackberries (superb!)
Italian or Carni?
My dream is to own a small farm someday, raise chickens and turkeys and maybe have a beehive or two.