Thw paper presents a new approach to constraint-based solid modeliing that supports the interactive construction and modification oj solid models using SD in. puI devices such as a spaceball or dataglove. The goal is to develop a more intuitive, graphically based solid rnodelling system that ezploits the advances in 9D input devices. This goal has been achieved by integrating direct 3D manipulation and procedural constraint propagation approaches. The main contribution oj the paper is a technique re~err-edto as allow- able motion that enables the accurate 3D posifionirrg of a solid model by automatically constraining its 3D manipuia. tions. Assembly relationship and geometric constratnt$ be- ttveen entities are automatically injerredfrom the 3D rnanijr. ulotion oj the solid model and stored in a Relationship Graph (R G). The allowable motion oj the solid model i., !hen com - pu(edjrom sta constraint Snjormatton In the R(;, .4 prototgpe system has b~en implemented to demonstrate the feasibility oj the approach. This system is capable oj automatically in- jerrvng assembly operations purely from 5'D manipulations carried out by the designer. The system also supports /he