There are several available model types:
If you intend to build a model on your own, look at the
FreeTrack project pages - it contains the "model" creation hints, tutorials and more.
There are several predefined models - "NP TrackClip", "NP TrackClip Pro", "Face", "Single point reflective" and "Single LED" - if you use one of those, just select the one of your choice in the Model Name combo box and you can continue to the next pane.
If none of the predefined models suits you, you can define your own.
Type your model's name to the Model Name box and then select the appropriate model type. Available model types are these:
Now fill-in the model dimensions (where applicable) according to the diagram (all dimensions are in millimeters). The last thing to do is to select, if the model uses LEDs (obviously with the exception of face model type) - if it does, check the Model with LEDs check-box. After pressing the Create button, the new model should become available in the Model Name combo-box for you to select it.
For example, the first slider in the 3 point Clip model tweaking panel allows you to minimize the back and forth head movement while looking left and right. To find the "sweet spot", employ the "halving of the interval" method, utilizing the fact, that at that point the movement is smallest and the movement direction reverses.
Move the slider to the left extreme and observe the Z axis (back/forth movement), while panning left and right - note the direction of the movement of the cross; for example, when looking left, the cross moves right and vice versa. Now move the slider fully to the right and see that the response is reversed (e.g. look left, move left).
The spot you are looking for is somewhere in between the two. Move the slider to the middle and see what the response is in there; for example the look left moves the cross to the right - which is the same direction as the leftmost slider extreme. That means, that the sweet spot lies in the second half of the interval (in this example). Now you can continue by repeating the halving it, or just try moving the slider around in small increments to minimize the movement.
Repeat the above steps for both (3-point Cap)/all three (3-point Clip) sliders to reduce the amount of the unwanted movements; if the result doesn't satisfy you, you can remove the rest of it by increasing the dead-zone for the axis of interest.