Kegerator Dual Tower Tap - Should I fill the foam void?

I'm creating a dual tower tap Kegerator out of a mini fridge and I have been looking at a lot of tutorials where the instructions say to dig through the foam at the top of the fridge, find the coolant lines and run the hoses through. For my project I am going to run the hoses through copper pipe.

After many tutorial reads, some people instruct to fill in the cut out foam void with spray foam. Others say that you should leave the void un-filled because it will act as an area that will collect cold air and cool the top of the tower. What is your opinion on this step?

Also, I know another way to do this is using a fan blowing air into a tube that runs up one of the pipes. I'm thinking about implementing this later. As a separate question, are there any fans / fan setups you would recommend?

Are you referring to where you dug foam out of the top of the fridge, or the void within the tower itself?

If you are referring to a tower, i haven't used one yet, but the fact remains that heat rises. I've seen threads where insulating the interior of the tower was found to be ineffectual, and I've seen threads where mounting a fan under the tower to circulate cold air up the tower was found to keep the lines cool.

Hopefully more people will chime in with actual experience.

I'm referring to the top of the fridge where I dug out the foam. Whether to fill it or not?

Yeah, you should probably replace any insulation you ripped out. But you may decide that you want the base of the tower to be open to push cool air through it.

Copper is a good conductor of heat, but i don't know whether it's a cure for warm beer lines in the tower.