Allows stacking of two IKEA Lack tables. The side marked with TOP is screwed onto the top of the bottom table with the brackets facing to the inside.

Due to the inside mounting, the outside dimension of the table remains the same.

Note that there should be a small gap between the border of the table and the border of the top plate. For convenience, I included a guide STL which can be printed and used for finding the right position (see photos).