diff --git a/app/src/main/java/com/codigoparallevar/minicards/CanvasView.java b/app/src/main/java/com/codigoparallevar/minicards/CanvasView.java
index 1119bca..e808942 100644
--- a/app/src/main/java/com/codigoparallevar/minicards/CanvasView.java
+++ b/app/src/main/java/com/codigoparallevar/minicards/CanvasView.java
@@ -478,4 +478,10 @@ class CanvasView extends View implements PartGrid {
         this._viewOrigin = new Tuple2<>(0, 0);
         this.invalidate();
     }
+
+    public Tuple2<Integer, Integer> getCenteredOn() {
+        int xOffset = _viewOrigin.item1 + getWidth() / 2;
+        int yOffset = _viewOrigin.item2 + getHeight() / 2;
+        return new Tuple2<>(xOffset, yOffset);
+    }
 }
diff --git a/app/src/main/java/com/codigoparallevar/minicards/MainActivity.java b/app/src/main/java/com/codigoparallevar/minicards/MainActivity.java
index 6018d58..390660a 100644
--- a/app/src/main/java/com/codigoparallevar/minicards/MainActivity.java
+++ b/app/src/main/java/com/codigoparallevar/minicards/MainActivity.java
@@ -1,17 +1,16 @@
 package com.codigoparallevar.minicards;
 
+import android.app.Dialog;
+import android.content.DialogInterface;
 import android.support.design.widget.FloatingActionButton;
 import android.support.v7.app.ActionBar;
+import android.support.v7.app.AlertDialog;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
 
-import com.codigoparallevar.minicards.parts.buttons.RoundButton;
-import com.codigoparallevar.minicards.parts.samples.ColorBox;
-import com.codigoparallevar.minicards.types.Part;
-
 public class MainActivity extends AppCompatActivity {
 
     CanvasView canvasView;
@@ -25,7 +24,7 @@ public class MainActivity extends AppCompatActivity {
 
     boolean devMode = false;
     FloatingActionButton removePartFab;
-
+    private PartsHolder partsHolder;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -43,6 +42,8 @@ public class MainActivity extends AppCompatActivity {
         canvasView = (CanvasView) findViewById(R.id.canvasView);
         canvasView.setParentActivity(this);
 
+        partsHolder = new PartsHolder(this);
+
         removePartFab = (FloatingActionButton) findViewById(R.id.remove_part_fab);
         canvasView.setDropZone(
                 removePartFab.getX(), removePartFab.getX() + removePartFab.getWidth(),
@@ -59,18 +60,7 @@ public class MainActivity extends AppCompatActivity {
         AddPartButton.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
-                if (canvasView != null) {
-                    Part buttonPart = new RoundButton(
-                            canvasView,
-                            500, 1200,
-                            80, 100);
-                    canvasView.addPart(buttonPart);
-
-                    Part boxPart = new ColorBox(canvasView,
-                            400, 1100,
-                            500, 1200);
-                    canvasView.addPart(boxPart);
-                }
+                partsHolder.openAddPartModal(canvasView);
             }
         });
 
diff --git a/app/src/main/java/com/codigoparallevar/minicards/PartInstantiator.java b/app/src/main/java/com/codigoparallevar/minicards/PartInstantiator.java
new file mode 100644
index 0000000..87804c7
--- /dev/null
+++ b/app/src/main/java/com/codigoparallevar/minicards/PartInstantiator.java
@@ -0,0 +1,15 @@
+package com.codigoparallevar.minicards;
+
+import com.codigoparallevar.minicards.types.Part;
+import com.codigoparallevar.minicards.types.PartGrid;
+import com.codigoparallevar.minicards.types.Tuple2;
+
+public abstract class PartInstantiator {
+    protected abstract Part instantiate(PartGrid grid, Tuple2<Integer, Integer> center);
+
+    public Part build(CanvasView canvasView) {
+        Tuple2<Integer, Integer> center = canvasView.getCenteredOn();
+
+        return instantiate(canvasView, center);
+    }
+}
diff --git a/app/src/main/java/com/codigoparallevar/minicards/PartsHolder.java b/app/src/main/java/com/codigoparallevar/minicards/PartsHolder.java
new file mode 100644
index 0000000..a772d42
--- /dev/null
+++ b/app/src/main/java/com/codigoparallevar/minicards/PartsHolder.java
@@ -0,0 +1,61 @@
+package com.codigoparallevar.minicards;
+
+import android.app.Dialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.support.v7.app.AlertDialog;
+import android.util.Log;
+
+import com.codigoparallevar.minicards.parts.buttons.RoundButton;
+import com.codigoparallevar.minicards.parts.samples.ColorBox;
+import com.codigoparallevar.minicards.types.Part;
+import com.codigoparallevar.minicards.types.Tuple2;
+
+import java.util.List;
+import java.util.Vector;
+
+class PartsHolder {
+    private final Context context;
+
+    private final static List<Tuple2<String, PartInstantiator>> BuiltInParts =
+            new Vector<Tuple2<String, PartInstantiator>>(){{
+                add(new Tuple2<String, PartInstantiator>("Round button", RoundButton.getInstantiator()));
+                add(new Tuple2<String, PartInstantiator>("Red/Green box", ColorBox.getInstantiator()));
+    }};
+
+    public PartsHolder(Context context) {
+        this.context = context;
+    }
+
+    public void openAddPartModal(final CanvasView canvasView) {
+        AlertDialog.Builder builder = new AlertDialog.Builder(context);
+        builder.setTitle("Choose part type")
+                .setItems(getPartTypes(), new DialogInterface.OnClickListener() {
+                    public void onClick(DialogInterface dialog, int which) {
+                        if ((which >= 0) && (which < BuiltInParts.size())){
+                            Log.d("Minicards partsHolder",
+                                    "Spawning " + BuiltInParts.get(which).item1);
+                            PartInstantiator instantiator = BuiltInParts.get(which).item2;
+                            PartsHolder.this.runInstantiator(instantiator, canvasView);
+                        }
+                    }
+                });
+
+        Dialog dialog = builder.create();
+        dialog.show();
+    }
+
+    private void runInstantiator(PartInstantiator instantiator, CanvasView canvasView) {
+        Part part = instantiator.build(canvasView);
+        canvasView.addPart(part);
+    }
+
+    private static String[] getPartTypes() {
+        String[] partTypes = new String[BuiltInParts.size()];
+        for (int i = 0; i < BuiltInParts.size(); i++){
+            partTypes[i] = BuiltInParts.get(i).item1;
+        }
+
+        return partTypes;
+    }
+}
diff --git a/app/src/main/java/com/codigoparallevar/minicards/parts/buttons/RoundButton.java b/app/src/main/java/com/codigoparallevar/minicards/parts/buttons/RoundButton.java
index f72a798..c27d6af 100644
--- a/app/src/main/java/com/codigoparallevar/minicards/parts/buttons/RoundButton.java
+++ b/app/src/main/java/com/codigoparallevar/minicards/parts/buttons/RoundButton.java
@@ -1,10 +1,10 @@
 package com.codigoparallevar.minicards.parts.buttons;
 
-import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.util.Log;
 
+import com.codigoparallevar.minicards.PartInstantiator;
 import com.codigoparallevar.minicards.ScrolledCanvas;
 import com.codigoparallevar.minicards.types.PartConnection;
 import com.codigoparallevar.minicards.types.Tuple2;
@@ -39,6 +39,8 @@ public class RoundButton implements Part {
     private final int _pathRunWay = 200;
     private List<OutputConnector> _outputConnectors;
     private final RoundOutputConnector _pressedOuputConnector;
+    private final static int DEFAULT_INNER_RADIUS = 80;
+    private final static int DEFAULT_OUTER_RADIUS = 100;
 
 
     private RoundButton(String id, PartGrid partGrid, int xCenter, int yCenter, int innerRadius, int outerRadius) {
@@ -249,4 +251,15 @@ public class RoundButton implements Part {
             input.unlink();
         }
     }
+
+    public static PartInstantiator getInstantiator() {
+        return new PartInstantiator() {
+            @Override
+            protected Part instantiate(PartGrid grid, Tuple2<Integer, Integer> center) {
+                return new RoundButton(grid,
+                        center.item1, center.item2,
+                        DEFAULT_INNER_RADIUS, DEFAULT_OUTER_RADIUS);
+            }
+        };
+    }
 }
diff --git a/app/src/main/java/com/codigoparallevar/minicards/parts/samples/ColorBox.java b/app/src/main/java/com/codigoparallevar/minicards/parts/samples/ColorBox.java
index 55819c4..3e08e40 100644
--- a/app/src/main/java/com/codigoparallevar/minicards/parts/samples/ColorBox.java
+++ b/app/src/main/java/com/codigoparallevar/minicards/parts/samples/ColorBox.java
@@ -6,7 +6,9 @@ import android.graphics.Paint;
 import android.graphics.Rect;
 import android.util.Log;
 
+import com.codigoparallevar.minicards.PartInstantiator;
 import com.codigoparallevar.minicards.ScrolledCanvas;
+import com.codigoparallevar.minicards.types.Tuple2;
 import com.codigoparallevar.minicards.types.connectors.input.InputConnector;
 import com.codigoparallevar.minicards.types.Moveable;
 import com.codigoparallevar.minicards.types.connectors.input.SignalInputConnector;
@@ -25,6 +27,7 @@ import java.util.UUID;
 
 public class ColorBox implements Part {
     private static final String TOGGLE_INPUT_CONNECTOR_ID = "toggle_input_connector";
+    private static final int DEFAULT_SIDE_SIZE = 100;
     private final String _id;
     private final PartGrid _partGrid;
     private boolean _activated;
@@ -228,4 +231,16 @@ public class ColorBox implements Part {
     public int getInputConnectorCenterY() {
         return (getTop() + getBottom()) / 2;
     }
+
+    public static PartInstantiator getInstantiator() {
+        final int halfSideSize = DEFAULT_SIDE_SIZE / 2;
+        return new PartInstantiator() {
+            @Override
+            protected Part instantiate(PartGrid grid, Tuple2<Integer, Integer> center) {
+                return new ColorBox(grid,
+                        center.item1 - halfSideSize, center.item2 - halfSideSize,
+                        center.item1 + halfSideSize, center.item2 + halfSideSize);
+            }
+        };
+    }
 }