In this paper, we define complex solids by real functions. Just from relatively small formulae we produce highly detailed complex objects and are able to manipulate and transform them producing more complex ones. We show how complex static and time-dependent objects can be created with the use of so-called R-functions. Then, we consider just one long-standing problem, hair modelling, and show how our functionally based model can be applied there. In modelling hair, we represent it with solid noise and subsequently unify it with the solid being made hairy. The hair and the solid are defined by real functions and the resultant hairy solid is in turn functionally defined and can be an argument for other operations. We are able to control length, thickness and curliness of hair and to obtain different hairstyles varying defining functions and applying set-theoretic operations to solid hair.