One thing I've found with using styrene as a building material, and using sheet-on-frame construction, is that you can be as rough as guts in the construction of the framework, but the cladding will still take on smooth lines.
Also, you can be fairly rough with the cladding as well, with cleanup using a dremel sanding drum or a mini file; or by using filler where the sheeting doesn't match up properly.
The photo below shows how I got my original Lines Plan wrong. I didn't recognise the error on the Plan, nor when I assembled the framework, nor even when I added the cladding to the sides, undersides and transom. It wasn't until I added the chine cladding that the error became apparent. But - filler to the rescue.
Des.