The rear and side frames of the shelves are made from 20 mm thick quality pine. The supports for the shelves are made from timber and are machined to fit into a groove on the underside of the actual shelf component.
The shelves are stackable [please view this disclaimer]. A dowel on top of the rear frame uprights is used to locate and prevent any lateral movement in the stacked units.
There is also a clamping plate that is attached to the bottom of the rear frame which will enable the units to be secured [with a clamp] to a table top. This element is removable if not required.
The two shelf version has the same features and dimensions as the standard unit but stands 60 cm high. It can also be stacked.