Dovetail gridfinity base - Magnet cleat/anchor v1

Insert for my gridfinity base modules to add an anchor to ferritic (steel) substrates, such as drawers or base plates.  Use one in each corner, opposite corners, or as you see fit.  Use 1-5 6x2mm magnets as you need.  It only holds the base module in place in 2 dimensions.  It does not clamp.