This effect looks great. Very easy to do. Well constructed and clever method. I don't really know
what else to say without giving it away. The only part that may require some real work would be if
you want to hand out the sharpie to be examined after the effect is complete. It requires a switch
with a fairly large object, but with a little misdirection the switch can be done in the open in
front of the spectator with no problem. I'd recommend it for sure. If you have big hands, (I have
very skinny hands with large "Windows"), you won't even need the misdirection. Just practice your
basic shuttle pass. Have fun!