Its not hard to do. I just penciled in the area to be flaps and cut out the area. Find a 3-view for refference. Trim down the ribs and add stock for hinge mounts. I made the flaps from thin ply with light fiberglass and epoxy on each side. I used Robart hinges and set them at a 90 degree angle when the flaps are closed. Hitec 225's mounted close the the cg. The Zero balloons up when first applied. I have added some down trim to the elevator but not flown since. Probably added 6 ounces total weight or less.

Carl