My panel is 17 3/4 inches (45 cm) high at the yoke and 46 inches (117cm) wide and of course it curves down at the top as you go to the sides. At the center bottom there’s a “tab” 18 cm wide that sticks downward and will mate up with a central console someday. So at the center, the panel is 23 1/4 inches (59cm) high. (Note that this 59 cm is partly the result of standard construction material in the US of 48″ by 96″, and a quarter of that is 48″ by 24″; pieces that size are readily available in hardware stores.) It depends somewhat on the hardware you’re going to use and just how cramped you want to be. A drawing from the web of a real C172 panel/cockpit gives a width of 100 cm and a height, floor to panel top, of 90 cm.