Q:

Cannot add ArcGIS ModelBuilder output to table of contents

I've made a model that creates some points with Z value and a buffer, which I then do a 3D analyst IDW on, and a Cut Fill analysis. 
The model input is a line along with af DEM/Raster, and some names for the output files. However I would like to show the IDW output as a layer that will be opened in the Table Of Contents and displayed as well as the CutFill, but for some reason I can't get it to work. 
Answer: Adding a Make Raster Layer after the IDW output seems to do the trick as well. 
Link for the toolbox with the model in it

A:

The answer is in the help file under the page title of Display model data, the note explains how to make it add to table of contents.
Quoting from ESRI help file:

Add To Display has no effect outside ModelBuilder. When running a
  model tool from its dialog box or the Python window, the Add To
  Display setting will not be honored. To add model data variables to
  the display when running the model from its dialog box or the Python
  window, make the data variable a model parameter, then enable the Add
  results of geoprocessing operations to the display option from the
  Standard toolbar: Geoprocessing > Geoprocessing Options > Add results
  of geoprocessing operations to the display.

