diff --git a/src/proc/play/dummy-play-connection.hpp b/src/proc/play/dummy-play-connection.hpp
index 5cefdbbd6..37681ce0f 100644
--- a/src/proc/play/dummy-play-connection.hpp
+++ b/src/proc/play/dummy-play-connection.hpp
@@ -81,11 +81,20 @@
 #include "proc/play/output-manager.hpp"
 #include "proc/mobject/model-port.hpp"
 #include "lib/time/timequant.hpp"
+//#include "lib/scoped-collection.hpp"
+#include "proc/mobject/builder/model-port-registry.hpp"
+#include "proc/asset/timeline.hpp"
+#include "proc/asset/pipe.hpp"
+#include "lib/query.hpp"
+#include "lib/util.hpp"
+//#include "lib/symbol.hpp"
+
 #include "lib/iter-source.hpp"
 //
 #include <boost/noncopyable.hpp>
 //#include <boost/scoped_ptr.hpp>
 //#include <string>
+#include <vector>
 
 
 namespace proc {
@@ -97,7 +106,7 @@ namespace play {
 //    using lumiera::DummyPlayer;
   using lib::time::Duration;
   
-  typedef lib::IterSource<proc::mobject::ModelPort>::iterator ModelPorts;
+  typedef lib::IterSource<mobject::ModelPort>::iterator ModelPorts;
   
   
   struct PlayTestFrames_Strategy
@@ -106,6 +115,101 @@ namespace play {
     };
   
   
+  namespace { // simulated builder environment
+    
+    using asset::Pipe;
+    using asset::PPipe;
+    using asset::Struct;
+    using asset::Timeline;
+    using asset::PTimeline;
+    using mobject::ModelPort;
+    using mobject::builder::ModelPortRegistry;
+    using lumiera::Query;
+    using util::contains;
+//  using lib::ScopedCollection;
+//  using lib::Literal;
+    using lib::eachEntry;
+  
+    typedef asset::ID<Pipe> PID;
+    typedef asset::ID<Struct> TID;
+      
+//  typedef ModelPortRegistry::ModelPortDescriptor const& MPDescriptor;
+    
+    
+    inline PID
+    getPipe (string id)
+    {
+      return Pipe::query("id("+id+")");
+    }
+    
+    inline TID
+    getTimeline (string id)
+    {
+      return asset::Struct::retrieve (Query<Timeline> ("id("+id+")"))->getID();
+    }
+    
+    const uint NUMBER_OF_PORTS = 2;
+    const string namePortA("bus-A");
+    const string namePortB("bus-B");
+    
+    /** 
+     * helper for dummy render engine: 
+     * Simulate the result of a build process,
+     * without actually running the builder.
+     * Produces some mock pipes, model ports etc.
+     */
+    struct SimulatedBuilderContext
+      {
+        ModelPortRegistry registry_;
+        ModelPortRegistry* existingRegistry_;
+        
+        std::vector<ModelPort> modelPorts_;
+        
+        /** setup */
+        SimulatedBuilderContext()
+          : registry_()
+          , existingRegistry_(ModelPortRegistry::setActiveInstance (registry_))
+          {
+            performMockBuild();
+          }
+        
+        /** tear-down */
+       ~SimulatedBuilderContext()
+          {
+            if (existingRegistry_)
+              ModelPortRegistry::setActiveInstance (*existingRegistry_);
+            else
+              ModelPortRegistry::shutdown();
+          }
+        
+        void
+        performMockBuild()
+          {
+            PID pipeA        = getPipe (namePortA);
+            PID pipeB        = getPipe (namePortB);
+            TID someTimeline = getTimeline ("dummy_Timeline");
+            
+            // start out with defining some new model ports......
+            registry_.definePort (pipeA, someTimeline);
+            registry_.definePort (pipeB, someTimeline);
+            
+            registry_.commit();
+            
+            // now "bus-A" and "bus-B" are known as model ports
+            modelPorts_.push_back (ModelPort(pipeA));
+            modelPorts_.push_back (ModelPort(pipeB));
+          }
+        
+        
+        ModelPorts
+        getAllModelPorts()
+          {
+            return eachEntry (modelPorts_.begin(), modelPorts_.end());
+          }
+      };
+  }
+
+  
   /********************************************************************
    * Framework for dummy playback and rendering.
    * A DummyPlayConnection provides a coherent set of placeholders,
@@ -118,13 +222,14 @@ namespace play {
   class DummyPlayConnection
     : boost::noncopyable
     {
+      SimulatedBuilderContext mockBuilder_;
       
     public:
       
       ModelPorts
       provide_testModelPorts()
         {
-          UNIMPLEMENTED ("provide a set of test model ports");
+          return mockBuilder_.getAllModelPorts();
         }
       
       POutputManager