This paper illustrates the possibilities to analyse complex or hybrid three-dimensional form-active structures. The structural model consists of pin joint elements, these represent either a cable element (tension) or a bar ' (compression).

The force density method calculates an equilibrium form for a cable net or a membrane within a given boundary. It is possible to modify the connectivity of the net (add nodes or links, mirror regions) or to change the structural attributes (turn a fixed node into a free one, change the stiffness, the force density of a link or modify the sag of a boundary). Compression bars can be modeled by means of a known unstrained length.

To obtain a powerful interactive tool the edit functions have been implemented within Autocad.

In this tool it is possible to copy and paste a set of elements, to group elements into a composed part and to 'procreate', which means that a set of elements is selected, transformed (translated, rotated, scaled or mirrored) and added to the global structure. Coincident points can be merged into one node to form a structural unity.

The examples show that with EasyER (Pre-processor), EASY (Formfinding and Analysis) and GEDEIN (Graphical Editor within EASY. from Technet) complex and hybrid compositions can be modeled and calculated.

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