I initially wrote this a while ago as a personal exercise, decided to give it a 2nd pass and find some tool to make match the pf2e formatting.
IMO, a core issue w/ the Alchemist is that everything they use can be bought from a store, or handed to an ally. No matter how you swing it, using buyable items is not a real chassis to build from. I remember someone accusing Alchemist of "being the closest thing to playing an NPC as you can get" and that kinda stuck with me.
My goal was to make something properly Alch, give it as much of a consistent structure on the front-end rules wise, and allow for the Contraptions to be as much of a blank check individually as possible.
All those ingredients led me to thrown-to-terrain deployables that are decided/prepped w/ Reagents each day, but can be refueled for multiple uses, and even in the worst cases, should steal an enemy action or two to smash.
This first pass was intended to a bit "one of everything" type listing, from a zone that invokes penalties to elemental typed saves, to raw utility like the Spectral Hand-Off.
The Enhancements are where things get real mad-scientist, such as enabling any Contraption to have it's elemental fuel type swapped for any other.
Overall, it really just brings the idea of item-fueled equipment from the Treasure Vault, gives it a formal structure, and actually makes them Alchemist-options, instead of once again letting any class use to full effect.
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Don't hold back, critique this however you see fit, whether that's one Contraption or Enhancement triggering an OP alarm, or some core rule.
https://scribe.pf2.tools/v/rvr6HTRd-alchemical-contraptions-v-1-1
(May want to zoom in a fair bit on this website for readability.)
Wrong forum.
I am hoping to get some feedback on this subset of rules / mechanics before posting a v1.2 to the homebrew forum at a later time.
Kind of a chicken-egg problem, hard to justify a 1-person's blind creation as worth posting to the homebrew section. But also hard to justify posting here to a pf2e rules forum.
Definitely flag it if you think it's in the wrong place.