One Of a Kind

[CosmoQueen]

How do I get the key out?

[Leon]

Well... if I tell you that, I'd spoil the game .. ;-)
Let's just say that you need to create some tools. I assume you're talking about the key in the watertank?

Then you'll need:

Spoiler

a broom, the calipers, the glue and a wooden plank

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Get creative and use everthing in your environment to craft a handy tool. Oh ... I hope you paid attention in science class..   

[Crimson Wizard]

Oh ... I hope you paid attention in science class..  

Haha.
Well, actually I wanted to make puzzles which require technical thought.
There are 2 possibilities. (but only one of them is achievable)
1) either make something that could bend behind the corner and catch a key.
2) or think what will make a key move aside out of the tube bend.

Oh yes, and for more hints -

Spoiler

Although you cannot interact it directly, but water is an object too

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