diff --git a/inst/include/common/model.hpp b/inst/include/common/model.hpp
index 251c9eb..af1a3a7 100644
--- a/inst/include/common/model.hpp
+++ b/inst/include/common/model.hpp
@@ -5,20 +5,21 @@
 #include "def.hpp"
 
 #include "../pop_dy/von_bertalanffy.hpp"
+#include "../common/data.hpp"
 
 template<typename Type>
 class Model{
     public:
 
-    std::vector<Type> data; //TODO: make sure data not empty
-    std::vector<Type> ages;
     std::vector<Type> predicted;
     std::shared_ptr< VonBertalanffy<Type> > vb;
+    std::shared_ptr< ObsData<Type> > obsdata;
 
     std::vector<Type*> parameters;
 
     Model(){
         this->vb = std::make_shared<VonBertalanffy<Type> >();
+        this->obsdata = std::make_shared<ObsData<Type> >();
     }
 
 
@@ -39,10 +40,10 @@ class Model{
    */
   Type evaluate(){
     Type norm2 = 0.0;
-    for(int i =0; i < ages.size(); i++){
-        Type pred = vb -> evaluate(ages[i]);
+    for(int i =0; i < obsdata -> ages.size(); i++){
+        Type pred = vb -> evaluate(obsdata -> ages[i]);
         this->predicted[i] = pred;
-        norm2+=(pred-data[i])*(pred-data[i]);
+        norm2+=(pred-obsdata -> data[i])*(pred-obsdata -> data[i]);
     }
     return norm2;
   }
diff --git a/inst/include/interface/rcpp/rcpp_interface.hpp b/inst/include/interface/rcpp/rcpp_interface.hpp
index 2d84e24..09efb1f 100644
--- a/inst/include/interface/rcpp/rcpp_interface.hpp
+++ b/inst/include/interface/rcpp/rcpp_interface.hpp
@@ -5,11 +5,20 @@
 
 #include "rcpp_objects/rcpp_growth.hpp"
 #include "rcpp_objects/rcpp_data.hpp"
+
+bool CreateModel(){
+  for (size_t i = 0; i < RcppInterfaceBase::interface_objects.size();
+       i++) {
+    RcppInterfaceBase::interface_objects[i]->prepare();
+  }
+}
+
 /**
  * Exposes the Variable and vonBertalanffyInterface classes to R.
  */
 RCPP_EXPOSED_CLASS(Variable)
 RCPP_EXPOSED_CLASS(vonBertalanffyInterface)
+RCPP_EXPOSED_CLASS(ObsDataInterface)
 
 /**
  * Returns the initial values for the parameter set
@@ -43,10 +52,11 @@ RCPP_MODULE(growth) {
     .field("estimable",&Variable::estimable);
     Rcpp::class_<ObsDataInterface>("ObsData")
     .constructor()
-    .method("prepare", &ObsDataInterface::prepare);
+    .method("finalize", &ObsDataInterface::finalize)
+    .field("Data", &ObsDataInterface::data)
+    .field("ages", &ObsDataInterface::ages);
     Rcpp::class_<vonBertalanffyInterface>("vonBertalanffy")
     .constructor()
-    .method("prepare", &vonBertalanffyInterface::prepare)
     .method("finalize", &vonBertalanffyInterface::finalize)
     .field("k", &vonBertalanffyInterface::k)
     .field("l_inf", &vonBertalanffyInterface::l_inf)
@@ -55,6 +65,7 @@ RCPP_MODULE(growth) {
     .field("beta", &vonBertalanffyInterface::beta);
     Rcpp::function("get_parameter_vector", get_parameter_vector);
     Rcpp::function("clear", clear);
+    Rcpp::function("CreateModel", CreateModel);
 };
 
 #endif
\ No newline at end of file
diff --git a/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp b/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp
index b8854f5..de71bd6 100644
--- a/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp
+++ b/inst/include/interface/rcpp/rcpp_objects/rcpp_data.hpp
@@ -8,14 +8,14 @@ class ObsDataInterface  : public RcppInterfaceBase {
 public:
     Rcpp::NumericVector data;
     Rcpp::NumericVector ages;
+    Rcpp::NumericVector predicted;
 
-    virtual bool prepare(){
-        
-        if(this->data.size() != this->ages.size()){
-            Rcpp::stop("ages vector length not equal to data vector length");
-        }
-        
-        ObsData<double>* obsdata;
+    template<typename Type>
+    bool prepare_local() {
+
+        std::shared_ptr<Model<Type> > model = Model<Type>::getInstance();
+        std::shared_ptr< ObsData<Type> > obsdata;
+        obsdata = std::make_shared<ObsData<Type> >();
         
         obsdata->ages.resize(this->ages.size());
         obsdata->data.resize(this->data.size());
@@ -24,7 +24,61 @@ class ObsDataInterface  : public RcppInterfaceBase {
             obsdata->ages[i] = this->ages[i];
             obsdata->data[i] = this->data[i];
         }
+        model->predicted.resize(this->data.size());
+        
+        return true;
+    }
+
+     /**
+     * Prepares the model to work with TMB.
+     */
+    virtual bool prepare() {
+
+
+        if (this->data.size() != this->ages.size()) {
+            Rcpp::stop("ages vector length not equal to data vector length");
+        }
+
+        this->predicted = Rcpp::NumericVector(this->ages.size());
+
+#ifdef TMB_MODEL
+
+        this->prepare_local<TMB_FIMS_REAL_TYPE>();
+        this->prepare_local<TMB_FIMS_FIRST_ORDER>();
+        this->prepare_local<TMB_FIMS_SECOND_ORDER>();
+        this->prepare_local<TMB_FIMS_THIRD_ORDER>();
+     
+#endif
+   
+        return true;
+    }
+
+     /**
+     * Update the model parameter values and finalize. Sets the parameter values and evaluates the
+     * portable model once and transfers values back to the Rcpp interface.
+     */
+    void finalize(Rcpp::NumericVector v) {
+        std::shared_ptr< Model<double> > model = Model<double>::getInstance();
+
+        if (this->data.size() != this->ages.size()) {
+            Rcpp::stop("finalize: ages vector length not equal to data vector length");
+        }
+
         
+        for (int i = 0; i < this->predicted.size(); i++) {
+            this->predicted[i] = model->predicted[i];
+        }
+    }
+
+     /**
+     * Print model values.
+     */
+    void show_() {
+        Rcpp::Rcout << std::setw(15) << "observed  " << std::setw(15) << "predicted\n";
+        //Rcpp::Rcout << "Predicted size: " << this->predicted.size() << std::endl;
+        for (int i = 0; i < this->predicted.size(); i++) {
+            Rcpp::Rcout << std::left << std::setw(15) << this->data[i] << std::setw(15) << this->predicted[i] << "\n";
+        }
     }
     
 };
diff --git a/inst/include/interface/rcpp/rcpp_objects/rcpp_growth.hpp b/inst/include/interface/rcpp/rcpp_objects/rcpp_growth.hpp
index f5ce0f6..823dae1 100644
--- a/inst/include/interface/rcpp/rcpp_objects/rcpp_growth.hpp
+++ b/inst/include/interface/rcpp/rcpp_objects/rcpp_growth.hpp
@@ -17,80 +17,65 @@ class vonBertalanffyInterface {
 
 
     template<typename Type>
-    void prepare_local() {
+    bool prepare_local() {
 
-        std::shared_ptr<Model<Type> > model_1 = Model<Type>::getInstance();
+        std::shared_ptr<Model<Type> > model = Model<Type>::getInstance();
+        std::shared_ptr< VonBertalanffy<Type> > vb;
+        vb = std::make_shared<VonBertalanffy<Type> >();
 
-        //        model_1->clear();
-        model_1->predicted.resize(this->data.size());
-        model_1->ages.resize(this->ages.size());
-        model_1->data.resize(this->data.size());
-        for (int i = 0; i < this->data.size(); i++) {
-            model_1->ages[i] = this->ages[i];
-            model_1->data[i] = this->data[i];
-        }
 
         //initialize k
-        model_1->vb->k = this->k.value;
-
+        vb->k = this->k.value;
 
         //initialize l_inf
-        model_1->vb->l_inf = this->l_inf.value;
-
+        vb->l_inf = this->l_inf.value;
 
         //initialize a_min
-        model_1->vb->a_min = this->a_min.value;
-
+        vb->a_min = this->a_min.value;
 
         //initialize alpha
-        model_1->vb->alpha = this->alpha.value;
-
+        vb->alpha = this->alpha.value;
 
         //initialize beta
-        model_1->vb->beta = this->beta.value;
+        vb->beta = this->beta.value;
 
 
         if (this->k.estimable) {
-            model_1->parameters.push_back(&(model_1->vb)->k);
+            model->parameters.push_back(&(vb)->k);
         }
 
         if (this->l_inf.estimable) {
-            model_1->parameters.push_back(&(model_1->vb)->l_inf);
+            model->parameters.push_back(&(vb)->l_inf);
         }
 
         if (this->a_min.estimable) {
-            model_1->parameters.push_back(&(model_1->vb)->a_min);
+            model->parameters.push_back(&(vb)->a_min);
         }
 
         if (this->alpha.estimable) {
-            model_1->parameters.push_back(&(model_1->vb)->alpha);
+            model->parameters.push_back(&(vb)->alpha);
         }
 
         if (this->beta.estimable) {
-            model_1->parameters.push_back(&(model_1->vb)->beta);
+            model->parameters.push_back(&(vb)->beta);
         }
+        return true;
         
     }
 
     /**
      * Prepares the model to work with TMB.
      */
-    void prepare() {
-
-
-        if (this->data.size() != this->ages.size()) {
-            Rcpp::stop("ages vector length not equal to data vector length");
-        }
-
-        this->predicted = Rcpp::NumericVector(this->ages.size());
+    virtual bool prepare() {
 
 #ifdef TMB_MODEL
-
         this->prepare_local<TMB_FIMS_REAL_TYPE>();
         this->prepare_local<TMB_FIMS_FIRST_ORDER>();
         this->prepare_local<TMB_FIMS_SECOND_ORDER>();
         this->prepare_local<TMB_FIMS_THIRD_ORDER>();
+        
 #endif
+        return true;
 
     }
 
@@ -100,11 +85,9 @@ class vonBertalanffyInterface {
      */
     void finalize(Rcpp::NumericVector v) {
         std::shared_ptr< Model<double> > model = Model<double>::getInstance();
-        std::shared_ptr<VonBertalanffy<double> > vb = model->vb;
+        std::shared_ptr< VonBertalanffy<double> > vb;
+        vb = std::make_shared<VonBertalanffy<double> >();
 
-        if (this->data.size() != this->ages.size()) {
-            Rcpp::stop("finalize: ages vector length not equal to data vector length");
-        }
 
         for (int i = 0; i < v.size(); i++) {
             (*model->parameters[i]) = v[i];
@@ -117,9 +100,6 @@ class vonBertalanffyInterface {
         this->l_inf.value = vb->l_inf;
 
 
-        for (int i = 0; i < this->predicted.size(); i++) {
-            this->predicted[i] = model->predicted[i];
-        }
     }
 
     /**
@@ -130,12 +110,6 @@ class vonBertalanffyInterface {
         Rcpp::Rcout << "k = " << this->k.value << "\n";
         Rcpp::Rcout << "a_min = " << this->a_min.value << "\n";
         Rcpp::Rcout << "l_inf = " << this->l_inf.value << "\n";
-        Rcpp::Rcout << std::setw(15) << "observed  " << std::setw(15) << "predicted\n";
-        //Rcpp::Rcout << "Predicted size: " << this->predicted.size() << std::endl;
-        for (int i = 0; i < this->predicted.size(); i++) {
-            Rcpp::Rcout << std::left << std::setw(15) << this->data[i] << std::setw(15) << this->predicted[i] << "\n";
-        }
-
     }
 
 };
diff --git a/test/test.R b/test/test.R
index acf7451..a7fd3be 100644
--- a/test/test.R
+++ b/test/test.R
@@ -39,13 +39,14 @@ vonB$l_inf$value<-7
 vonB$l_inf$estimable<-TRUE
 
 #set data
-vonB$data <-data
+Dat <- new(g$ObsData) 
+Dat$Data <- data
 
 #set ages 
-vonB$ages<-ages
+Dat$ages<-ages
 
 #prepare for interfacing with TMB
-vonB$prepare()
+g$CreateModel()
 
 #create an empty data list (data set above)
 data <- list()