Take a large thick cardboard box. Cut it into planar pieces. Take transparent tape and cover the cardboard's surface with it. Tadaa! A whiteboard:

Because transparent tape is smooth the whiteboard pen is erasable.

Sticky notes stick a lot better on the transparent tape than on the cardboard, which is useful for Kanban Boards!

Ideally, put white paper between the cardboard box and the tape to get an actual white board.

This method can be applied to convert any object into a whiteboard, like a big piece of wood, the side of a shelf, your forehead, etc.

(Originally my intention was to make sticky notes stick better, and accidentally discovered that I made a whiteboard. That's why I did not use white paper.)

(I'm currently unsure if there is a problem with the pens becoming unerasable when leaving them on for a long period of time, or any other problems, as I just came up with this.)