Specifying requirements for a multimedia system is difficult and is often carried out in an informal way. Requirements engineering in information systems development is, on the other hand, often done in a more formal and thorough way. The chapter suggests that the difference is due to the interactive and dynamic properties of the multimedia user interface. A large proportion of the functionality has to be defined relative to the end users who are not experts in formulating system requirements. Successful multimedia requirements engineering is often characterized by close contacts between end user and developer; both parties have knowledge that needs to be shared mutually. One way to identify and formulate the requirements would be to work in a laboratory environment where end users themselves can try their ideas regarding interactive products. This is the motive for an on-going construction of a GUI experimental station reported in this chapter. The set-up is intended to admit non-programmers to test ideas for interactive products. This trial concerns educationalists focusing on persons, mainly children, suffering from various language disabilities. The aim is to facilitate manual simulations of the interactivity of teaching aids proposed by the educationalists now and in the future, thereby simplifying testing and making the development of ideas during test runs possible. The paper discusses manual simulation in relation to production of interactive teaching aids and other multimedia products.