I have several recipes to make your own slime, left over from when our kids were the right age. (I never delete anything!) Let me hunt them down. Back in a minute...
METRIC SLIME
20 ml boiling water (1 Tbsp. + 1 tsp.)
30 ml Borax detergent (2 Tbsp.)
80 ml water
80 ml Elmer's Glue-All (white)
Food coloring (optional)
(Note: Do not use water-soluble "school" glue or gel-type glue.) Dissolve Borax completely in 20 ml boiling water. Mix 80 ml water and glue to milky liquid. Add food coloring if desired. Blend with borax-water solution. (Start with a utensil. When it no longer moves freely, use clean hands.) When all the liquid has been worked into the semi-solid, and no liquid-filled bubbles remain, you're done. If water remains in the bottom of the bowl and cannot be blended in, add more Borax-water. Finished consistency should resemble Gak™ and will slowly "flow" like a liquid even if broken into pieces. If consistency is too liquid, allow Slime to sit uncovered on a flat surface (such as a plate with a rim, an aluminum pie pan, or a Frisbee) overnight to allow some of the water to evaporate. (Break away and discard any edges that becomes crust-like.) Store in airtight container suitable for holding liquids. Don’t forget to keep it away from carpet, upholstery, etc.
PSYLLY SLIME
This version has ingredients the grandparents may already have in the house, but requires a microwave.
1 tsp. Metamucil or psyllium husk
Blue or green food coloring
1 1/4 cups water
Combine the Metamucil or psyllium and the water in a jar. Put the lid on tight and shake until it mixes. This might take a few minutes. Pour the mixture into a glass container that can go in the microwave, and add a few drop of food coloring. Have an adult microwave the mixture on “high” for either three minutes or until it starts to ooze out of its container. Let it “rest” in the microwave for three minutes, then microwave it on high for three more minutes. Have an adult use potholders or oven mitts to take it out—it will be very hot. Wait at least an hour before you try to play with it, or you could burn your hands. Store in airtight container suitable for holding liquids. Don’t forget to keep it away from carpet, upholstery, etc.
(Stovetop: Medium-high heat until it boils, then boil for about ten minutes. See Valenslime recipe for test to show it's ready.)
VALENSLIME
6 tsp. Metamucil or other powdered fiber supplement
6 c. water
Red food coloring (optional)
Combine water and Metamucil (and food coloring) in a large saucepan, stirring to dissolve the powder. Bring to a boil over medium-high heat. Continue to boil the mixture for 15 to 17 minutes. The mixture will decrease in volume and become thick, and it will cling to a spoon when you stir it. Test for doneness: If you turn off the heat and tilt the pan a bit, running a spoon across the bottom of the pan should leave a clear path for a few seconds. You want it to be thick, but not so thick it turns solid and rubbery.
Pour slime into a large bowl, baking dish, or rimmed cookie sheet and allow it to cool. If it still seems too wet, you can return it to the saucepan and reheat it.
Divide the slime into smaller blobs. One batch should make about ten good-sized portions.
Package slime in snack-size plastic bags, squishing the slime into one side of the bag and folding the excess to make a neat square package. (Make sure you don't break the bag's seal.) Print and cut cards to fit the bags and tape slime package into the bag. Better than a store-bought valentine!
MONSTER SLIME PARTY FAVORS
¼ cup Borax detergent powder
1 cup white glue
1 quart water
Food coloring
Paper cups, stir sticks, sealable plastic bags
(Note: Do not use water-soluble "school" glue or gel-type glue.) You can make your own version of gooey slime, sold commercially as Gak™, in give-away quantity. In advance, dissolve 1/4 cup Borax (sold in the laundry detergent area of supermarkets) in 1 quart of water and set aside. In a large jar, pour 1 cup glue, 1 cup water and a few drops of green or orange food coloring. Cover and shake hard. At the party, pour 2 tablespoons of the Borax solution into a paper cup and stir in 6 tablespoons of glue solution with a Popsicle or crafts stick. The mixture will become thick and slimy. Stir hard, then pour off any extra liquid. Kids can knead it with their hands, then play with it. Send it home with them in sealed plastic bags with “Sticky Stuff” warnings already printed on with a marker.
I would not consider any of the versions made with Borax or glue for bodily insertion, and food coloring stains horribly, including clothing, linens, and grout. Maybe try the Psylly Slime, if any?