Splined miter cuts. The carcase is assembled with miters and reinforced with splines. To allow for uniform expansion, cut spline material to fit with the grain going the same direction as the sides of the carcase . Assembling the carcase Because the plywood-core panels minimize wood movement, you can glue the top and bottom to the sides of the carcase. Tape up the mitered carcase joinery.
Tape helps hold the joints in place before the clamps go on.
After applying tape to the outside of the mitered joints, flip the assembly and coat the mitered ends with glue. Assembling the carcase. Once glue is applied to all the joints, tape helps hold the carcase assembly in place. When the assembly is clamped up, use winding sticks to check the flatness. Glue up the carcase first, then fit the drawer to the opening.