Tetrahedral models of organic molecules are cheap and make attractive talking points. All that’s required is a photocopier and spray paint (or heavy coloured copy paper). With enough time there is no limit on the number of items. Sheets of nets in pdf form are linked below for single bonds: hydrogen, carbon, nitrogen, oxygen, fluorine and chlorine: one double bond: carbon, nitrogen, oxygen, and a triple bond carbon or nitrogen. Additional nets are included needed to model benzene and the oxides of carbon and nitrogen.