When designing a scratching post for cats, the most important thing to consider is the height of the post. It should be tall enough for the cat to stretch and scratch comfortably, but not so tall that it becomes a hindrance.
Next, think about the surface texture. Cats prefer a smooth, scratchable surface like sisal or corrugated cardboard. Anything too rough or sticky will drive them crazy.
Consider the base of the post. A wide base will prevent it from tipping over, but a narrow base will allow for more flexible positioning in a room.
Finally, don't forget about aesthetics. Your scratching post should be an attractive addition to the room, not a eyesore.