Flubber is a jellylike substance that is made in school science classes as a fun project or as an amusing plaything for children, similar to Silly Putty. However, most recipes for flubber include borax as one of the main ingredients. Borax is a toxic substance and even a teaspoon of borax could seriously harm a child (Resource 1). It is not safe for pets either. Therefore, an ideal non-toxic flubber will not contain borax. Metamucil is an excellent substitute for borax. It is an edible fibre supplement, the main ingredient of which is psyllium seed husks. When mixed with liquid, it forms a gel.
Take a teaspoonful of Metamucil and place it in a jar with 23,954ml of water. Put the lid on the jar. Shake the jar for about one minute.
Pour the Metamucil and water mixture into a microwave safe bowl and place it in the microwave. Microwave the mixture on high until it starts to rise up. You will need to keep a close eye on it; this should take about five minutes. Take the bowl out and let the mixture cool down a bit. Then you need to put it back in the microwave and repeat the process a few more times--five or six times maximum. The more you microwave the flubber, the more solid and rubbery the final texture will be (Reference 1). You will need to check each time you take the bowl out to make sure that the mixture does not become too solid.
Prepare a flat platter or baking tray before taking the flubber mixture out of the microwave when it is done. Pour it carefully and slowly onto the platter or baking tray, taking care that the flubber does not touch anyone's skin or splatter, as it will be extremely hot. Let the mixture cool down. Stir it constantly with a spoon as it cools (Reference 1).
Cut the flubber into pieces and store it in plastic bags when it is completely cool. This will keep the flubber fresh and sufficiently moist, and it will last for several months. If you refrigerate the bagged flubber, it will stay fresh even longer (Reference 1).
You can add food colouring when mixing the Metamucil and water in the jar (Step 1) if you wish to make coloured flubber (Reference 2).
This Metamucil-based flubber recipe requires the use of a microwave and therefore should be made under adult supervision.