The casing is intended to be an ingredient in craft recipes for machines. It isn't actually used in any recipes yet. Although mainly a craft item, it is defined as a node type, mainly to get an appropriately cubic inventory image. It is incidentally possible to place it as a node: this makes some sense, although the empty machine casing isn't actually useful as a node.
Technic
License
Copyright (C) 2012-2014 Maciej Kasatkin (RealBadAngel)
Technic chests code is licensed under the GNU LGPLv2+.
Texture licenses:
RealBadAngel: (WTFPL)
- Everything.