Bug with the sound *sorry*
This video shows how to make THE pardox in the portal 2 editor.
First, put a Laser with a receptor. Then, connect the receptor at the laser and enable it.
You can realise this with a glass plate. Disconnect the receptor at the laser and connect the receptor at the glass plate. It's better for use it
![](https://i.ytimg.com/vi/pnEg8m_dlDQ/maxresdefault.jpg)