Coloring Book of Magic - Small 8"L x 5.5" W
You know the gimmick coloring book that you can show as blank, line drawings or the line drawings colored in, depending on how you flip the pages. Now you can get the same thing in three sizes.
The benefits include:
1) A smaller prop fits a smaller or closer audience. Like a restaurant table or a small circle of kids.
2) The small one fits in a shirt pocket. 8"L x 5.5" W
3) The medium one fits (original size) into a large clown pocket or most magic cases. 11" L x 8.5" W
4) The big one works well in a living room or a small crowd. Extra Large 14" L x 10.5" W
That's all nice but I like the fact that they are exactly the same except for size. I'd come up with a three book Monte routine. It would require the clown logic of discounting the fact they are different sizes. Show two books colored in and one book blank. Ask them if they can follow the blank book. Mix the books up and have them choose. I might let them win a few times to make it into a running gag. Just a thought.