The present invention provides a system or kit which includes plastic components which can be readily assembled to form a structure with the use of a minimal number of tools. The components are precut so that measurements and cutting of the component materials is eliminated. This leads to a savings in wasted materials. The components are readily assembled using conventional fasteners and simple hand tools. The components have preformed notches and tabs in order to facilitate assembly of the components without the requirement for measurements. This assures that the components will be assembled correctly and eliminates the opportunity for inaccurate measurements and incorrect assembly. The enclosure is provided with a sliding roof panel and pivoting doors which permit easy access to the interior of the enclosure.