I want to create the characters of South Park in 3D, I can do the body, head and shoes fairly easily but the eyes, hat, arms and hands are more difficult. Could anybody make a quick tutorial for this please?
You can import an image of the character and trace it (line, arc, ...). There are several tutorial about this topic online, one example:
Sorry I did not specify my needs properly, the character needs to be 3D not 2D.
You should check the 3d warehouse:
I've already seen them, not quite the quality I would like but it's a good start.
Unfortunately, because this is such a specialized request, it is likely to be the best you will get unless you perform the task yourself, or unless another South Park aficionado responds.
I think the 3D Warehouse quality is decent. For South Park I don't think the characters need to be that detailed. But that's just my opinion.
I've seen someone do a livestream on designing the South Park characters on the creative livestreaming platform picarto.tv (which is for artists only, unlike Twitch) but that was a few months ago and I can't remember who the user was, but it was really interesting to watch. Livestreaming in general can be quite interesting to learn from others and interact with them.
Stop looking for such a specific tutorial, instead read and watch generalized lessons to learn the fundamentals of modeling in SketchUp. This will provide the answers you seek which will apply to not only this project but almost all other projects you may want to complete.