You mean this would be used as building? For example changing brick wall into marble?
If you mean something like that, it would be cool, but instead of just tool I think it could be available as some advanced building menu that every QOL wouldn’t require forge or materials.
Hold a stack of ‘x’ in left hand, have tool in right hand, aim at the area you wish to change (vertical or horizontal), and it swaps all the blocks in that plane (to whatever size you forged on the tool) to ‘x’.
I think there could be ways to do this without forged tool or have option between forged tool and epic skill.
I see that it could work for example this way: hold plot view key/button for short while and there shows (radial) menu where would be advanced building options like replace mode, rotate block, lock block texture direction (which could be copied same aim way like you describe), scaffold mode (temporary blocks) and more building options that would make building much more easier.
Something like on this suggestion but would be available for all without need of forge or new item