diff --git a/content/case_evaluation.tex b/content/case_evaluation.tex
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@@ -40,3 +40,25 @@ I expect that these improvements would have had a significant impact on the desi
 
 
 
+
+\section{Development Cycle}
+\subsection{Design and model}
+            Prior to the case study I expected the model to be the design.
+            So when the level of detail of the design is increased, this is achieved by expanding the model with more detail or components.
+            Resulting in different versions of a single model where each version has more detail than the previous one.
+            However, during this development a 2D dynamics model, 3D dynamics model and a 3D component model.
+            Although these models have components in common, they are not compatible.
+            Therefore, adding detail to the design requires two or three models to be updated.
+
+            Furthermore, the step from 2D to 3D physics was in no means a small increment in detail.
+            The first four levels of detail, as describe in the previous section, all were implemented in with two dimensions.
+            As the later details required a third dimension, all the detail was directly converted from 2D into 3D.
+            This is a large amount of work, introducing a high cost when the conversion fails.
+            Moreover, it creates a new 3D physics model, parallel to the 2D physics model instead of adding detail to the latter.
+            Alternative approaches for 3D model physics could be:
+            \begin{itemize}
+                \item Ignore 2D and start implementation in 3D modelling.
+                \item Retrace all incremental detail steps of the 2D model in a 3D model.
+            \end{itemize}
+            Both options are not ideal, the first one does not allow a simple basic model and the second approach redoes work.
+            The advantage of starting with 3D is that allows for a continuous development of one model, instead of switching the complete model.