Here we go!
Step 1: You will notice when making multiple adjacent surfaces that there are very tiny gaps in between them. There is a very simple way to fix this.
Step 2: Select the surface knitting tool by going to Insert > Surface > Knit
Step 3: Then, select the two surfaces that you want to knit. There is an option for "gap control". For a model like this that is unnecessary.
Step 4: Click okay and the two surfaces will be "knitted" together. No more gaps!