PlasticGun/src/main/resources/data/plasticgun/recipe/composite_resin.json

{
  "type": "minecraft:crafting_shapeless",
  "ingredients": [
    { "item": "minecraft:slime_ball" },
    { "item": "minecraft:clay_ball" }
  ],
  "result": {
    "id": "plasticgun:composite_resin",
    "count": 2
  }
}