box there may be provided knobs the length and width dimensions of which fit the width of the grooves 4 such that the stave elements may be connected to the box when the base shape of the knobs is square the stave elements may be mounted along the box sides or perpendicularly protruding therefrom while the elements may furthermore be outwardly or inwardly projecting in all directions when the knob shape is circular the lengths of the box sides are proportioned in such a manner that by use of some of the stave elements these may be joined and laid out as a structure on the box sides e g with corner joints as shown in fig9 and a transparent lid l associated to the box as shown in fig1 39 may then be placed as a roof over the thereby constructed 34 hall 34 many different objects may very well be comprised in or added to the system and need merely be designed for being joined with or to the stave elements e g erect fence portions or lamp posts for guided insertion into the grooves 4 or model houses which at their underside are provided with downwardly protruding pins 8 or holes 12 for cooperation with the.