transparency

Hi! 

I created a 3D rectangle in Indesign using only lines. How can I fill that "rectangle" with white color so that it's not transparent? Since it's not recognized as an actual rectangle, it doesn't fill it for me. I need to stack these 3D rectangles for a project I'm doing but don't want the lines from the rectangle underneath to be showing. 

Anyone know how to fix this?

Thanks!