To make the rubber holder:
In a pot, mix the konjac, kappa and water evenly. Heat to 80°C, stirring constantly until it becomes a clear gel.
Transfer it to a tall narrow container (as tall as the dildo). Allow the temperature of the gel to cool to 50°C and then dip the dildo in it.
Remove the dildo and verify that there is a fine transparent layer on its surface. Wait a few seconds until the fine gel layer sets. Remove it carefully, as if it were a condom. Set aside on a clean cloth.