I completed the bed platform I started building last week today. I added horizontal slats, which serve two functions. The spacing allows the mattress to “breathe” while the 1/2″ thickness permits them to flex, adding a modest amount of give to the foundation. The slats are floating to allow them to bend. Fixed spacers provide permanent alignment. I can’t wait to test the feel of our mattress on the new frame. If it needs to be firmer, I can replace the slats with thicker ones, and should it be too firm, with thinner ones. I will probably need to wax the slat support surfaces to prevent squeaking during vigorous activity on the mattress. I am looking forward to that aspect of testing.