For this interesting DIY cactus terrarium you will need a glass jar, a cactus, stones or crocks for drainage, charcoal to keep mould & bacteria at bay, soil and sand. Put stones or crocks onto the bottom, add a generous sprinkling of charcoal, then a mixture of sand and soil. Carefully plant your cactus inside then add a layer of sand to top it off. You can add some decoration at this stage.Enjoy it.