Create-Design-n-Decor/src/generated/resources/assets/design_decor/blockstates/black_metal_sheet_slab.json

{
  "variants": {
    "type=bottom": {
      "model": "design_decor:block/black_metal_sheet_bottom"
    },
    "type=double": {
      "model": "design_decor:block/black_metal_sheet"
    },
    "type=top": {
      "model": "design_decor:block/black_metal_sheet_top"
    }
  }
}