Whiteboard eraser based on Bi-office dimensions

Salvage a magnet or have 1cm deep 40mm x 25mm.
Added varying heights of 35 mm, 40 mm and 45 mm separately.

Video - https://www.youtube.com/watch?v=ML8y-xw9CJY&pp=ygUIaW5mYXR1bTk%3D