Beginner looking for help: An easy way to put a lot of parts together and get just the outter shell (For 3D printing)?

[Kevin256]

Hey everyone!

So for my final college assignment I decided to give myself a challenge and try / learn something new. I sketched an anime character and almost finished modeling him. I am also going to 3D print the figure.

Now the problem is, that I must connect all the parts and of course I made myself a mess by creating too many objects (Like really a lot of them) that need to be connected. Some even with different number of subdivisions.

I would appreciate if someone would help me and tell me a way to join them AND ALSO how to only get the outter shell. For 3D printing, there can't be any inside parts.

Thank you so much everyone!