Go to your local ACE hardware and pick up a piece of 1/4" white polypropolyne plastic.... drill 2 holes for the retainer pegs, than follow the contour of the medallion giving yourself an extra 1/2" all around and machine down 1/8" removing all the plastic material between the lines..... then just place the white plastic piece inside the seat push on the retainer tabs til the sunk-in effect starts to take place an your done.

Later, BUZZ