I really like interesting challenges grounded in player skill or player worldbuilding like this or Chris from iTO’s traps post on his blog.
I think we can make some more. This could be a place to put those things. Do you have a puzzle you are particularly proud of?
This is one of the traps I’m most proud of. Included in my puzzle dungeon, The Seers Sanctum
Two platforms seperated by a pool of water. Levers on the far side.
The water level is about one foot belong the surface of the platforms.
One of the levers controls the water level of the pool.
If this lever is flipped, the pool will drain over 10 minutes. If the lever is flipped again, the water will refill over 10 minutes. The first time this happens, a Gelatinous Cube is released into the pool having been squeezed through the pipes that fill the main pool. It reforms to its natural 10’x10’x10’ state.
The extra space occupied by the cube causes the water to overflow onto the north and south platforms by about an inch.
Something shiney and tempting is contained in the cube’s transparent mass. Players see the temptation in the pool but not the cube. They have the clues to work out that something else is in there too and hopefully don’t just dive in.
So the clue is the overflow, right? They could work out that something was in there if they just think about it…
Sort of reminds me of this trap from one of the Narnia books. Basically a pool of water is clear and at the bottom is a tall golden, statue of a human like figure.
The statue is gold because everything that touches the water turns instantly to gold, and the statue was once a real man.
I like that. Hopefully the party prods the water first. Rewards that experimentation.
With the gel cube pool I’ve seen PCs prod the water once before it drains and refills but then assume the water is still safe after it has refilled. I do make sure to emphasize that things are different to how they were before.
Also, players love pulling levers. I think every time I’ve run this the party always pulls the lever a second time to see if the pool refills.
These are such wonderful resources, thanks for posting them!
What if they do!?! What’s the cool follow-up to your whole plan being ruined? 
Well instead of just trying to get the treasure out of the cube, the PCs will also be trying to get their companion out as well. And with a time limit. 
Some of my entries for my d100 table This Secret Door Opens… might fit the bill for smaller scale puzzles and interactivity. I also really enjoy things like Magic Items that serve as very specific tools to solve problems (even if the problem is unknown at the time), and some of these manifest on things like my d100 Unconventional Potions table.
i wrote these 15 secret doors: https://drive.google.com/file/d/1RN29YQf7kuVnNtf-npOz7CsXC91ABNij/view?usp=sharing
There are other ideas here: Beyond the Black Gate: Megadungeon: Random Trap Disarming Table.
The post says disarming traps but imo they work better as secret door mechanisms
I just ran this for the first time and hoo boy do i feel silly for not realizing the cube was part of the puzzle. The emphasis on it being transparent should’ve been a clue forehead slap