So, in order to get the best possible pressure cookers with current rescources, you should
1) make 13 pressure cookers, with highest possible purity
2) harmonize ore x25 (or more, if stuff explodes)
3) smelt harmonized ore
4) curse, because you got no bars, and forgot to do a low purity run to single out smelters that will yield a bar on next pure run
5) harmonize high purity ore x25 (or more, if stuff blows up again)
6) smelt harmonized ore
7) harmonize clay x4 (or more) and harmonize iron
8) craft unbaked pressure cooker
9) harmonize unbaked pressure cooker
10) bake pressure cooker
11) harmonize freshly baked pressure cooker
12) repeat from 5, 12 times, until you have 13 harmonized pressure cookers
13) repeat from 1