Profile
The edge of the cupboard unit is not straight. As we want to fix a door to this part Brian needs to cut a filler piece of wood with the same profile as the side panel to level it up. So off he went to his workshop to create the perfect tool for the job, which involved drilling a hole in a piece of wood and poking a pencil through it. He was then able to hold the point of the wood against the cabinet and drag it downwards, drawing onto the piece of wood he had prepared for the filler.
Genius! A perfect fit, and a straight edge to work from.