The top and sides of the Sonata Plus are made of 1mm thick steel. The exterior surfaces are painted glossy piano black. This gives the case a conservative, yet classy look.
The paint job was good, with no defects and the surface looking even throughout.
On the inside of both of the side panels and top panel, there is a polycarbonate lining to help dampen noise. The interior sides of the panels are unpainted.
The bottom of the case is also painted piano black. To help absorb vibrations big rubber feet are in each of the corners of the base.