One of my favourite tools is my Japanese Shinto rasp. It is a precision piece of kit and it is one of the best rasps I have ever had but it is some times just a little too big, and other times a lot too big. This little tool make it into the spaces where the bigger rasp will not go. It could be thought of as a manual dado blade.
I bought a pack of a dozen hack saw blades from a two dollar store. For this one I snapped three of them in half to give me 6 blades 150 mm long.