A creative block That can be double-sided using all core full blocks!

I have been dreaming about a gray block with diamond/iron/gold corners that can be clicked on by another block ie, A book shelf and only half the block turns into that said block ie bookshelf and the other half could be clicked on the other side (side to side or top to bottom) making that a mixed block. The Mixed blocks dont drop after destroyed or provide any drops. Mixed blocks would be able to be destroyed by TNT and can be moved by pistons. Mixed blocks also have the potential if not for creative only by making the item harder to craft using diamond/iron/gold corners, stone in the middle, and item frames on the sides to complete the Mixed _Block. If only decided for creative it can only be given by going through creative or command/command blocks.