Temporary structures designed for longer or shorter periods of time are increasingly implemented using construction scaffolding systems – in these cases, the scaffolding system is a means of architectural expression of transition. From a structural point of view, stiffening the resulting square grids with diagonal rods is an exciting task. The aim is to create a rigid, stafly structure with as few elements as possible. Grid brace is one of the much-researched areas of structural topology [1,2] . During the TDK, we deal with the spatial extension of a variation of the plane  task: the aim is to create a small grid, say 4*4*4, with an ’empty’, say 2*2*2 kubus. The task can be approached by elementary means (including  modelling), but it is an advantage if it is chosen by a student interested in linear algebra and graph theory.