A one piece assembly of a small production unit (23) for panels intended for building comprises an upper tray (2) a bottom tray of longer length (1) a collapsible crane (7) situated on the upper tray (2) supporting the crane structure (7) is horizontally mobile with rollers (11) supported on rail (12) positioned on the bottom tray (1) without requiring an external support lying on the ground. The vertical movement of the upper tray (2) is assured by an assembly of screw jacks (4), plates (18), guides (14) and runners (13). The compact assembly (23) of the production unit can be moved from site to site without heavy handling movement.
