In theory, actually crafting things takes a significant amount of time. Arrows can be produced in a day, but a suit of chainmail might take several weeks before you can complete it, and for minimal profit, even if you can get 70% of it's actual value.
On the other hand, profession/performance rolls, for a week of work, will net more in the long run. You could do a commission process for characters and get partial, if not full payment in advance, but the characters are still looking at potential weeks of wait
I'm not complaining, just pointing out the difficulties. Lets not get into what spell casters who can enchant items will make for a couple of days of work. Staffers are almost set to take creat magical weapons/armor or iems at next level. They need Masterworked items, but how many will be set up to do theier own crafting?
Anyway, just thoughts.
As both skills have a weekly roll to allow for income, and both require, in theory, a full days work for a full day's pay, can you do both crafting and a profession roll at the same time?
Example (Ignoring masterwork as few would be able to make those roles consistantly at 1st level), say the average cost of a weapon (the less expensive of the high income skills) is 10GP. Or, 100 SP. Making average rolls, will take at least 2 weeks of work for a cost of 3 GP, 3SP and 4 CP. If you got 1/2 of it's value, you made less than 1.5 GP for two weeks of work.
On the other hand, a single profession roll might net you, with an average roll, 5 or 6 GP a week. There's still a flaw there. True, the more expensive items, the more you'll make, but it'll be hard to make money that way.
Ideally, selling weapons/armor to other characters would be best, but that would be commission work. Selling to those who enchant would be better, but that gives an enchanter the potential of huge amounts of income for a couple of days of work for what is a couple of days of work, once someone can reliabbly make masterwork items for them.