I have been playing an alchemist since round two of the play test, about half way to 17th now. I don't think I will ever play anything else. I have been thinking that while there are a lot of cool alchemy Items out there, Could we think of more.
I have been thinking about doing something with the idea of the Baghdad Battery. Some kind of alchemist spark, I think there was something like that in 3.5 don't remember where.
so what are some other item every one has homebrewed up for there games or anything related to alchemy in general?
I didn't really need to homebrew items so much as re-write ones from all of the books I had from the 3.X splat era. The main two extra books I drew from were the Ultimate Equipment Guide (Mongoose Publishing) and the Kingdoms of Kalamar Players Guide (Kenzer and Company).
Ultimate Equipment Guide has a lot of stuff, but next to nothing has Craft DCs, and much of it has only prices. They're scattered in with all of the other equipment (it's sorted by ideal class or general use, so there's some in every chapter), and there are a few cases of redundant items of wildly different quality (there's two versions of adhesive gum- one can hold ~20 lbs, the other can hold 200+ lbs, without much price difference). A number are dastardly broken (Rusting Orbs), others are inferior to cheaper items from the PHB (Flare Paste). But enough of them are pretty clever that it was worth re-writing them.
Kingdoms of Kalamar has quite a few good items in its equipment section, and generally errs on the side of underpowered (especially Mooreta, the anti-perfume). A few of their items are really, really missing enough description to be usable in a practical sense (merfolk musk), but it wasn't a bad addition. Some of the craft DCs are far too high for what the equipment did.
Both of them also had poisons, good for the alchemist, and since my concept at the time included being a brewer, I threw in the various alcohols in as well. UEG had some interesting brews.
Since I had over 100 items (I think) I could make fairly quickly with alchemy after scouring four books, we (my DM and I) came up with the idea that my Alchemist would know 1 recipe for every point of intelligence to start with (not mod, full score) and every rank in Alchemy. I could add more as I came across them, and they would generally cost 5 times what a single dose/use/container costs to buy the recipe from a dealer (one that was willing to deal, anyway). This set-up kept me from being McGuyver and having an item for every challenge, but let me be get mileage out of my skill and class abilities.