I'm not sure if they ship outside of the USA, but for casting from a mold, look at the products from Alumilite or Smooth-on.
Smooth-On - Mold Making and Casting Materials for a World of Applications!
They sell the casting plastic that will float or sink.
Casting Resin and Silicone Mold Making Rubber
Sells the clear casting plastic plus microballons to make their plastics float.
Also, check the lure makers products from Larry Dahlberg's site - www.huntforbigfish.com.
He also has a great DVD on lure making covering both hard and soft baits.
Good luck.
Gary