are you including materials from dragon mags? if so, there is one feat that has an interesting effect due to the wording. the feat "theurgic creationist" from dragon mag 325 on page 62. you have to have an item creation feat, and the ability to cast spells from two different spell lists. while an artificer has the first requirement down pat, they don't cast spells, requiring at least one level each in two other spellcasting classes. the benefit of the feat is that you get to add "all your caster levels" when qualifying for item creation feats or creating magic items. artificers do have caster levels as part of their class features.
the intention of the feat appears to be to allow a dual caster class character to create magic items as if they were a single caster class in either class by allowing them to add the caster levels from both classes together.
however with the addition of two "practiced caster" feats this can be subverted. roughly put, take a level of wizard, a level of cleric (or any other two classes that give access to two different spell lists) and then at least 4 levels of artificer. at first level take practiced caster for your (in this case) wizard or cleric levels, at third you take it again for the other class. at sixth you take the theugic creationist feat and add up "all your caster levels", as described in the feat.
which equals 1 from wizard, plus 4 from practiced caster-wizard, plus 1 from cleric, plus 4 from practiced caster-cleric, plus 4 from artificer; totaling 14 (or 16 for scrolls due to the artificer ability). take one more level of artificer to gain that capture essence ability... you're going to need it since trying to make items with that high caster level will quickly exceed your limited experience. it is suggested that you first make a +10 to umd skill item so that you can make the dc's to emulate the other aspects of crafting those high level items... all at 6th (or 7th) character level.
a friend of mine came up with this, and despite intensive research, this one seems solid... assuming that dragon mag materials are allowed in the first place. as it is, this will likely serve as yet one more reason not to allow dragon mag materials. ^^