Design of plastic formwork panel for concrete casting

I would like design of a one piece plastic panel to be used in concrete formwork. Panel size at face to be 1000mm x 500mm. Thickness of panel to be 100mm. Of this 100mm thickness, 20mm to be of solid plastic faceplace (face in direct contact with concrete). The remaining thickness to be made of reinforcing plastic grid skeleton. Plastic grid skeleton to be made in square grid shape with straight lines. No curves or fancy shapes that will make plastic moulding difficult. Material to be used in final product is PET or HDPE. Panels to be produced via heat compression moulding during manufacturing phase. The job of the engineer is to design the reinforced grid skeleton in order to keep panel stiff and rigid when under pressure from concrete during pour. Panels will be made to cast concrete walls 3000mm in height and 150mm in thickness, so each panel must resist deflection under these pressures. Concrete is to be mechanically vibrated for short period of time, so be sure to increase calculated pressure by 15% to allow for this. The job of the engineer is also to provide detailed calculation of any deflection in panels made of either PET or HDPE plastic, so that I may assess what grade formwork this is under Australian Standards. Engineer must also provide dimensioned Autocad and/or solidworks file detailing panel design. Thankyou