The aim of this study is to explore designers' preferences between randomness and control in the generation of architectural forms. To this end, a generative computer tool was implemented that allows both random and controlled generation of elements. An assignment was given to fourth-year Architecture students which involved the designing of several megastructures using the tool. Results show that both randomness and control can have their own space and play a complementary role in design. Most students were willing to explore randomness and were able to exploit it to generate good designs. However, some of them have certain degree of preference for more controlled solutions