A formwork for precast concrete panel comprises of a quadrangle panel with a base and four side panels. The formwork (10) comprises of a base (14), which is provided with an island region (20) and/or a mound region (22), a pair of parallel fixed spaced apart side panels (16) and a pair of parallel moveable side panels (18). The island region (20) and/or mound region (22) is positioned between the parallel moveable paced apart side panels (18) and wherein said parallel moveable spaced apart side panel (18) are removeably secured to the parallel fixed spaced apart side panels (16) in a tight manner in any desired distance from the center of the island (20) and/or mound (22) region.