Got the patterns finished today. The original casting on the right and one of the patterns on the left. The extra blocks of wood on each side of the wings and the two protrusions on the top are for the sand cores.
Bottom view. The blocks on each side are core prints. These create voids in the mold that will hold the sand cores. This allows us to draw the pattern out of the sand without destroying the mold. The pink in the middle is body putty that we used to create fillets between the ribs and the base plate.
The wing patterns. There's an extra piece of plywood on the side of each wing. This helps us to line the pattern with the base plate. Once we have holes drilled for our alignment dowels, these pieces will come off.
Drilling holes for the dowel pins to keep the top half aligned with the bottom half. You can see that extra piece of plywood that we use for aligning the wing with the base plate on the left side of the wing. This piece will be removed once we have the holes for the dowel pins drilled.
Once we have the alignment holes drilled, we glue 1/4" wooden dowels in the holes in the wing part of the pattern so that they protrude about 3/8". You can see them sticking out on the left side of the photo below. We next cut the dowels protruding on the top part (right side) of the wing pattern, then sand them so that they are flush with the top surface of the pattern.