http://www.d20pfsrd.com/feats/general-feats/master-craftsman---final
Close. The feat says that you use the chosen skill for the check to create the item. Therefore, you don't need spellcraft.
However, you are correct that the DC of the craft check increases by 5 for each spell you don't have.
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So besides the craft skill I need spellcraft which increases by DC 5 for each spell I don't have?
No. When crafting an item, you have the option if using the appropriate Crafting feat or Spellcraft.
For example, if you are trained in Craft (Bowyer), you could use that when you are making a magical bow instead of Spellcraft.
Now, to separate out the other part, the DC to make a magic item is 5 + caster level, normally. For a +1 longbow, for instance, it would, normally, be 5 +3 (CL3 for a +1 weapon), or 8. Now, if, somehow, a second level PC somehow wound up with the Craft Magic Arms & Armor feat, and wanted to make that +1 bow, and had the money for it, the DC would become 8, the base, +5 for not having the required caster level of 3, for a total DC of 13.
Note that Master Craftsman only unlocks access to Craft Magic Arms and Armor, and Craft Wondrous Items, and maybe only only a limited subset of each, IIRC.
So, with Master Craftsman, you need to be 5th level before you can take it, so 7th level, probably, before you can take the Crafting feat. Assuming Craft as a class skill, level number of ranks in it, and a 12 Int, at 7th level, your base in Craft (x) would be 7 ranks +1 Int +2 Master Craftsman +3 Class for a minimum of +13 and a caster level equivalent of 7, so +2 armor or weapons would be an easy check, at DC 11. +3 weapons or armor, with a required caster level of 9, would be DC 19 (5 base +9 CL+5 missing CL), so doable with a Take 10, but it may not be in your PC's price range. That DC goes up if you want to give it a special ability, instead of a simple enhancement bonus.
The abilities all list a CL and possibly spells needed, so that can add up.
Example: Fortification, Light:
+1 bonus
CL 13
Spells: Limited Wish or Miracle
So, DC is 5 + 13 +5 +5 = 28
Base + CL + missing CL + missing spell
That 13 Craft (X) would give you a chance at it, 25%, but not a good one, and missing it by too much (50%) can cause it to become a cursed item instead.
Also, it doesn't let you qualify for Craft Ring, which was listed in your OP, or Rod/Wand/Scroll/Potion/Staff.
Just Craft Wondrous Items and Arms/Armor.
Which is a shame.
IMO the feat is specific to arms and wonderous items for thematic reasons instead of mechanical ones. Crafting other items are just as thematic, and since doing so is more difficult for the master craftsmen compared to a spellcaster (due to the requirement of the craft skill and an extra feat), it would be hardy overpowered to allow crafting of potions, rings, and constructs.