Pen tube bookmarks! by -leethal-, via Flickr For when you can never find a pen to write in your notebook....and you can't find the page either.....what a genius idea! The tube holds the pen and the button holds the marker in the right place, even if the book is in the bottom of your bag, I should imagine! $5 for the pattern on Ravelry. or you could try to figure it out for your self!