Looking for a sturdy small booklet in bright colours ... 

check out this retro cahier with camera.

You can use this cahier to write and to draw on the 
blank pages. The paper is a bit thicker - 100 grams - 
so your fineliner won't end up at the other side of the page :)
Because of it's very limited size, it fits every bag or pocket.

Sometimes simple things can make you happy!