Create Reference Planes in 3D
Here is a little demo of a couple of macros to create Reference Planes in 3D. Revit doesn't really allow you to do this OOTB (which is sad as it is really easy to do in the API). The two VERY simple macros I created are...
ReferencePlaneByFace - Simply select any face and it will create a Plane. If the face in not a Planar Face then the face will be evaluated where selected and create a plane tangent to the point you picked.
ReferencePlaneByThreePoints - This allows the user to select 3 arbitrary points and create a plane from this. I must grumble here as sadly Revit doesn't really allow you to use snapping in 3D (well it does, but it is evil and should either be removed from the API or fixed so it is usable and doesn't require ugly workarounds when user changes the view cameras pos/rot and having to adjust the projection plane - clearly there is this function built-in, just wish Autodesk would expose it). Grumble over.
Both these methods allow for offsetting the plane and which side the plane should be offset. Hopefully this should make working in 3D a little easier, especially when working with faces.