need some hint about implementing burr puzzle

I think it will be interesting to make a burr puzzle.

But should I use physics contraint to confine the movement of the pieces or just rely on collision? I am a bit at sea.

Well, you could also create the puzzle with the solution in mind.

Means, each piece has a unique number and if I understood the puzzle, you can move 1 or more pieces at a time, right?

So you would have a locked and an unlocked state for each piece. The ones that can be removed are set to unlocked.
If the user finds them, a click will remove them (just an example of course). When a piece is removed, it will tell
the next piece that it gets unlocked.

Of course that means the solution for a puzzle needs to be known.

You could also rely on collision, but I haven’t solved such a puzzle yet. So I don’t know if the pieces just slide out.

A few line traces in the move direction to check if a piece is blocking somewhere could also work.

Relying on physical collision could cause a mess though. That’s why I would try to fake it a bit.

That’s a tough one, because you’re moving the tiles free.
Maybe try to make a 3D Grid, and stick the tiles to the grid when they’re close to a free spot.
So the game makes the handling easier.

Only collision though, no physic.