2d scene into 3d scene

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3D

Unity

2D

I have made a puzzle in 2d scene and now I want to put it in complete 3d scene. Is that even possible? How can I do that?
In 3d scene, I want to put it where is visible and the player can access it with key on keyboard or somehow like that. Put first that is my problem, so I'd be happy if you can help in any kind of way.
The 2d puzzle is made out of a uploaded picture as an asset. Then on the sprite editor, I cropped it in 6 pieces and added certain box colliders to each of them so then you can control the puzzle with mouse-click, then a script for making them rotate and then another one for control of the game in case when the player completes the puzzle.

What I have tried:

I have heard about making some type of object in 3d scene where then I can apply the puzzle, but I also don't know how to do it.