Good questions canman, probably there are many answers. Blacksmith hammers most used are probably between 2 and 3 pounds in weight. The cross peen might be used slightly more than the straight peen, but almost everyone will have both. A ball peen is necessary as a third hammer, a light one, and a heavier one makes four. A 4 pound hand sledge is five, an 8 pound sledge is six, a rounding hammer is seven, a deadblow or a soft hammer is eight and nine, a leather mallet and a wooden one is ten and eleven. Then there are different weights of any of the mentioned styles and there are diagonal peens, sharp peens, blunt peens, no peens, Quadra-Peens, etc, etc. Some people have three or four dozen hammers, but you can do most everything you want with only 5 or 6. As to what to make one out of, most any steel 1045 and higher carbon can be used. 4140, 4340, and O1 are steels I have used as well.