Afetr completing coating of the sides and top of the descent stage, you should start coating the underside. Prior to that you need to build the landing gear chock mounts which are made of 1 mm styrene rod at 1/32, the length of the rod is about 4.5 mm so you should use rods a bit longer to count for the part of the rod that is inserted into the descent stage underside. The picture on the upper right side shows how the chock mount is positioned