Make it as large as you can afford. Mine is a 12x12 room and is not nearly large enough, but better than what I had as I didn't have any room before, just strung out and stored everywhere in the house. I have a friend who has a 20 x 40 room and it is full to the brim, so figure out what area you need for your individual hobbies and then add several feet to it if you have the means and space to do it. I like the idea of the cedar lined closet and storage room too, so plan for future expansion if you can afford to do so. You won't be sorry with too much room, but will with too little of space.