There are many web pages that instruct you how to easily make your own solar cooker, it could be a cardboard solar box cooker, for example here , or a more sturdy one using wood shown here and you can find many suggestions on the solar cookers international website which will guide you to many different types of cookers, here are just a few examples:

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Hinged Panel Cooker This is a DIY panel cooker made from a kit I designed. As opposed to the original cookit it is made of rigid board pieces connected with hinges. So its life time should be much longer than the cardboard type.

DIY Box Cooker
This is a box cooker I designed using 5mm thick ply-wood, a single Polycarbonate glazing and newspaper crumpled up for insulation.