From Valve Developer Community
- Allow Physics Gun (gmod_allowphysgun)
<boolean>(Only in Garry's Mod)
- If set, players cannot use Physics Gun on this entity.
- Sandbox Tool Whitelist (gmod_allowtools)
<string>(Only in Garry's Mod)
- If set, only given tools can be used on this entity. You need to supply the tool class names, the names of the .lua files of those tools. This also includes the context menu properties!