To ensure that everything definitely fit together before throwing an adhesive into the mix, i concocted a dry assembly of the main body/ frame of the cabinet. This included the two rebait pieces, making up the top and base of the cabinet and the two sides and the backboard piece of veneered 3mm hardwood ply, that slots into the groove routed along the back edge of the solid walnut pieces. The box itself had no problems joining accurately, with 90 degree square inside the box, checked using and engineers square. However, i ran into some problems when trying to slot the back board in, which a thorough sanding of the groove wouldn’t fix. The veneer on both sides, made the back board too thick to fit into the 5mm groove, however cause the wood had already been cut to size there wasn’t any tolerance (without the runners hitting the backboard) to increase the groove. Therefore i decided to route the inside face of the veneered backboard, removing the layer of veneer along the edge of the backboard, where the board would be hidden within the groove. Checking again, this method had solved the problem, the backboard now successfully fit into the groove and the box could be sealed, held together using a four corner clamp, pulled taught and fastened.