Craft Skill

Crafting may seem the most lucrative skill to chase if you are not familiar with D&D's history on player crafting. There is money to be made here for sure but it's pretty awful compare to something like playing an instrument.  Even an idiotic barbarian that trains his skill in drums to it's fullest extent will make more reliable income with just a basic drum than the more genius expert will make crafting armor with the most basic tools.
But, both the barbarian and expert in the above examples have the option to get more advanced tools and assets to help them get further, yet still it sucks for the crafter because the crafter has to put money into every project and doesn't get paid until both the project finishes and they find a buyer. The Barbarian and his drumset gets paid as he plays. THe expert may take days, weeks, months, or years to finish some projects and then once they are finished, still have to find a buyer.
That's right, an expert's armor could take a year to make.
Crafting formulas and steps make perfect sense if you ignore the entire thing and don't look closely.
First you take the price of the item and multiply it by 100 to your workload in copper.
So if you are the expert above and you want to make a chain shirt. It has a price of 100gp, so you convert that to 10,000cp. 10,000 is now the workload you need to complete to have that chain shirt in hand as an actual item.
So your first step is you have to pay 1/3rd of that in crafting materials that you use to make the item. In this case it would be 3,334cp worth of iron. 
Then you have to make skill checks to make progress now. You start at 0 and have to make it to 10,000.
To make progress you make a skill check then if you beat the DC you multiple your results by the DC. In the case of armor the DC is 10+ the DC bonus of the armor in question. The chain shirt is 4AC so a DC of 14.
At about level 5 a character hoping to specialize in craftin should have an intelligence of 19, so a +4 to craft from their intelligence. Then +8 from skill ranks. Then a +2 from Masterwork tools. Then a +2 from a competence ring. This all comes together for a total of +16 to craft meaning even if you roll a nat1 you will still be at a 17 vs 14 so you can't possibly fail. But for generosity sake let's assume that you roll a 10 each time. So with your 26 vs the DC of 14. You succeed and produce a workload of 364 each day. At this rate it will take you 28 days of downtime to finish this chain shirt. In that amount of time you could raid a couple different dungeons and make a couple thousand gold then just buy one for you and all of your friends.
But you can boost it further. Make better tools. Get better rings. But those take money and time. One good free option is make friends with a cleric and harass them for that Guidance of the Avatar spell once a day. It's a free +20 to any single skill check. Turning that 26 into a 46. So now with a roll of 46 and that DC of 14  means a daily workload of 644. Taking it down from 28 days to 16 days. Still sucks though doesn't it?
There also exists a rule that allows you to rush your crafting by artificially boosting the DC of your work in increments of 10. So we already know that even at a nat1 you can't fail. And now you are getting an extra +20 from Guidance of the Avatar. So now if you toss an extra 20 onto that DC to raise it to 34 and you still roll your 46 then your total workload per day will be 1,564. So not it will take you only 7 days to make their armor. Still not exactly impressive but a huge improvement over 28 days. 
By the time you get to level 8 you will get 3 more skill points and the ability to raise your intelligence by 1 point changing that modifier from a 4 to a 5. Plus if you increase your competence ring from a 2 to a 5, you now have a total increase of 7. Meaning even if you increase the DC from 14 to 24 you can't fail on a nat1. But if you take into account guideance of the avatar for another +20 you are now at minimum of 45 so you can increase that DC from 14 all the way to 44 without risking failure. Assuming you get your usual 10 you can achieve a roll of 53 against the DC of 44. Your workload will now be 2,332 so you would only take 5 days to make that chain shirt.
At this point you are finally making more money than the performer. But it is certainly less... roleplay rewarding.