So basically there is that lid on it with the light attached for veg stage. When it comes time for dark periods, I simply throw a big black sheet over everything and turn off all the lights. Once vegging is done I will hang the HPS and adjust it accordingly, and use the lid I had for veg stage as added height/extend the box. It's quite simple and was fun to build. The little holes at certain corners were done on purpose for air circulation/heat.

Comments/Questions?