add the unflavored gelatin, the sugar and the water to a heavy saucepan. bring to broil stirring constantly with a wooden spoon. when it boils a little, add the flavoured gelatin.
let ir boil until the mixture gets thicker and a film layer is formed at the surface of it. let it boil a little bit more and lower de fire.
soak a loaf pan with cold water and put the mixture in it. let it rest all night long or until the mixture is hard enough.
take the gum out of the pan and cover both sides with sugar (with the flavoured gelatin tastes better, but it's up to you).
cut the shape you want and cover the sides with more sugar (or gelatin).