Add in the slime activator a little at a time. Just until clumps start to form. You can make your own activator by mixing 1 cup warm water with 1 tsp of borax.
1 Cup Warm Water, 1 tsp Borax
Mix and stretch it until it becomes a stretchy slime.
Add the Key Ingredients for Butter Slime
Add in some lotion. Start with a small amount (~1/2 teaspoon)
1 Tbs Lotion
Mix in the cornstarch, a little at a time.
¼ Cup Cornstarch
Continue mixing in cornstarch until the slime becomes matte, instead of shiny. When you stretch it, it should be slow to stretch and have little ripples that hold their shape, like in the image.