Once the sides and corners have been glued together, it is possible to begin the assembly of the chest.
Having taken precise measurements to locate the sides on the bottom frame, you may glue and clamp both sides. And be careful to differentiate the sides from the drawer openings. If you want a standard chessboard, you must make sure that the bottom right corner for each player is a white square. Hence if your frame is not perfectly square but slightly rectangular instead, you must use strategy in the gluing process.
For this chessboard, my second one, the frame is sufficiently wide to be used to support the bottom of the drawers. Otherwise, it would be necessary at this stage to cut, plane and glue bottom supports to the bottom frame.
I then move on to the center support whose purpose will be to prevent the chessboard from sinking in the middle. I make this support out of a piece of scrap wood taking measurements and cutting indentations in the corners to make adjustments with the top frame possible.
Once the center support is glued, I add the drawer guides on the sides. Those do not have to reach all the way in to the center support. And like the bottom guides (or bottom frame depending on the design of the chest), the side guides must be made of tight-grained wood to facilitate the sliding of the drawers.
For the next stage, we will move on to the drawers!