I bought some used headlights for my 2015 lexus from Craigslist, they came with no ballast. Anyhow I went to a shop and they installed plug and play hid lights. So my problem is what can I use to cover the hole where the ballast was? I know it ain't safe to drive around especially in the rain, I don't want to ruin anything else.

 

YOu might need to find that piece from a junkyard. Maybe ebay or rockauto might have that piece

 

Post a picture of that hole that you want to cover. Not all of us have HID lights with ballasts.