Next, I cut a hole in the lid of my container and fed the light kit cord through the hole. I used the lid on the bottom of the container, and taped around the hole the cord came through so that no concrete would come through when I poured it. 

 Next I placed tape over the top of the light kit to protect it from concrete.

 I put the whole thing into a larger container for any concrete that got out. Now, the directions to the concrete package said something vague like "add water" and that adding more water meant "less firm concrete". The first batch of concrete I mixed was "soupy"  (seen below), and that worked fine, when I needed more concrete for my mold, I made it thicker and that worked fine as well.....so don't stress about the consistency too much. Now the concrete will set fast, so you will need to work quickly, but you do have a minute or so to maneuver things and get them just the way you want. I held the light fixture while Connor poured the concrete in the cracks, and then with my finger I made sure it was level.