Sift sugar, cornflour and gum tragacanth into a heatproof bowl. Heat gently in the oven or over a pan of boiling water until the sugar feels warm.
Sprinkle the gelatin onto the water in a heatproof bowl and leave to stand until the gelatin has absorbed all the water. Dissolve it over a saucepan of hot water or in a microwave (do not allow the mixture to boil as this would destroy the elasticity). Remove from heat and add the fat and liquid glucose.
Pour the liquid and the egg white into a well in the centre of the sugar mixture. Mix in a heavy duty electric mixer on the slowest speed until the sugar has been incorporated. Increase the speed to maximum and mix for 5 to 10 minutes or until the paste is white and stringy (use of a dough hook will place less strain on the mixer).
Put the paste into a strong polythene bag and leave it in a container in the refrigerator overnight.
Next day, bring to room temperature. Smear hands well with white fat and knead the paste well, adding more fat if it is sticky.
As this paste dries out very quickly, it must be kept covered at all times. To use, cut off only a small quantity and store the remainder in the refrigerator.