A mod where you could move bricks with a tool but not destroy them.
If you had a 1x1x3 or the "spam block" you could transmute it into a 1x3x1 or an L shaped block by choosing in your brick selector.
All the blocks available to transmute would pop up in your brick hot-bar.
The plastic game-mode is kind of like this.
You would get all the bricks to make the structure as a variable, then you would build the thing back, you could also save the structure as a macro. You would have to build a transmutation circle OR have an item with a GUI every player on the server would have.
