Mixed Layer Specification - CompactMods/CompactCrafting GitHub Wiki
The mixed layer type allows for full control over every space in the layer. You must defined each block explicitly.
{
"type": "compactcrafting:mixed",
"pattern": [
["C", "C", "C", "C", "C"],
["C", "-", "-", "-", "C"],
["C", "-", "D", "-", "C"],
["C", "-", "-", "-", "C"],
["C", "C", "C", "C", "C"]
]
}