I want to make something almost toy-like for players to interact with in my dungeon. Sort of tools that they might use in ways I can't predict (hopefully without breaking the campaign).
My current idea is containers that do things. The type of container could vary depending on the vibe of your dungeon: jars, chests, stone alcoves, or pools. I like the idea of containers with lids. That way you can't watch what happens to what you put in the container, it's a mystery until you open it again. But I like pools too, maybe the liquid in the ppols will turn opaque when something is placed in them. Other features of the liquid in the pools could be determined as a potion.
Here's a possible lay out of pools and what they do:
Bb: Item placed in B will disappear. A tiny replica in brass/plastic/wax will appear in b. Removing and replacing the replica in b will cause the original item to appear in B. Think a 4th dimensional wharehousing device.
Cc: Item placed in C will disappear and reappear rejuvenated/younger in c. Item placed in c will disappear and reappear in C aged.
Dd: Item placed in D will be coated/plated/painted with material of whatever item is in d, using up that item completely.
E: This pool will subject whatever is placed into it to temperatures from hot enough to melt metals (1) to cold enough to flash freeze (2).
Ff: Item placed in F will be transmuted completely into material of item placed in f, using the item in f up.
G: Item placed in one of these pools will appear completely disassembled, its constituent parts floating above the other pool. Parts placed in one of the pools will appear assembled floating above the opposite pool. Living objects can go through this process generally without harm (a human re-assembled without their heart wouldn't do very well, for example).
Now, I know these seem a little too rational, like microwave ovens of the elders. And I toyed with the idea of pools that did weirder things, like cover objects in hair. But as a player myself, I don't think I would ever use that kind of device after a laugh or two. These others I might make a dangerous trek just to use. F is potentially campaign breaking, but if it is in a dangerous enough place, that and encumbrance might make it feasible.
I like B, and can envision a dungeon with little wax crowns and royal regalia scattered about it befuddling players.
What would fascinate you in an alien machine as a player?