I just have build a real thin board, made with a 2,5mm plywood core und 10mm concave in 138 x 38. After covering with 3 X 65 g/m2 carbon-Kevlar on deck and bottum and some Carbone in the middle it was really soft . After Stiffing it with 8 cm thin strip in 10 layer Carbon UD and cloth on the heelside and some extra layers in the middle it is really fine. Good grap and nice Pop. Weight is normal.