How do I make a block that can't be stacked or placed on walls?

make an item that places the block, then make a procedure when right clicking on a block, check what face of the block the player is facing, if the player is facing a wall (west, east, north, south) when right clicking with the item place the block and set the block's rotation to match the wall's rotation, also consume the item when placing the block.

first set your block's rotation to face the block's face where you placed it.

you can make then a tag with blocks that you don't want to be stacked togheter , then add to the item's right click procedure, check if the wall has the unstackable tag, if true then don't place the block.

Hopefully i was helpful , it is quite hard to understand and it needs some advanced procedures , hopefully you'll understand what it wrote.

Have a nice day

-Fred

the problem i am having is i made a custom wooden log but i cant place it on top of its self like a normal log i cant build up with it anyone know how to fix this