Hi @Begad.Elmelligy 

Here are just a few ideas but let us know if that helps or not:

• We have some corner cubes models under https://support.zemax.com/hc/en-us/articles/1500005488341-How-to-model-corner-cube-retroreflectors?
• Thorlabs provide some CAD examples on their website: https://www.thorlabs.com/navigation.cfm?guide_id=2539.
• We also have a Ray Rotator object to function as a retroreflector. The Ray Rotator is an imaginary device that rotates all incident rays. For example, if you want the Ray Rotator object to behave as a retroreflector, you can first set its Material as Mirror and then set its 'Rotate Z' to 180 degrees. Now the Ray Rotator acts simply as a retroreflector to reflect and rays will propagate back along the same path as they came.