Solid extrusions rendering as hollow

Hello everyone, quite a simple request here but I would ask that someone take a look at my rendering screen shot.

I was wondering why my solid extrusions are coming out at hollow and how I can fix this, its my first rhino model I made so its kind of badly put togther which I suspect to be the issue however,

some kind of technical knowledge would be useful in solving the problem.

Thank you and happy new year!!

@ccini3376 , welcome to our Forum, and thanks for your first post. You can gladly send me the project file itself and I can let you know what the problem is here. Thanks!