I quickly present my current project (4 years already): construction as compliant as possible of an alfa 33 stradale.
I've been working on this project for 4 years and have already acquired limited skills thanks to it... on solidworks.
the chassis is completely designed all I have left is the verification of the constraints or the .... I'm incompetent but I'll find someone to help me.
My current problem is twofold...: 1st simplest problem I think; I can't cut my 3D representation of the bodywork into "printable slices " in order to reconstitute it as a 1/3 scale and then 1 scale model, for example.
My second more delicate problem I think..... I have access to a 3D printer and want to validate the steps of my drawing..... this on a scale of 1/18 then 1/8...
However, I am faced with the impossibility of thickening my surfaces..... in order to print ... In my case thickening to 8mm allows me to print on an ultimaker2.
wanting to print only the shell .... I have of course trouble sewing with the option to form a volume since there are lots of holes .... (air inlet windows .... etc)
I imagine that these are rays or other segments that are too small that block the peeling ...
Starting with a project like this, it's true that it's not easy.
The choice of functions used is essential to achieve the desired result.
Personally, I would have gone for a volume to design a model to be 3D printed. I'm not an expert in the field, but I think that the surface is mainly used to represent "digitally" finite models.
I will therefore advise you to redo everything in volume. But I could be wrong.
This is something that may take you some time, but at least on the right footing, you can finalize your project perfectly. =)
I am attaching a small supplement of Solidworks used to separate your volume into several parts that can be assembled a bit like "Lego"
Looking at your 3D, we see that it is not "perfect" (no misinterpretation, I would like to get to your level on the surfaces! :) ). Look at the attached image, the connection between the "coda tronca" and the underside of the rear window. We can see that the fillet passes under the surface of the underside of the telescope. With that, there is no chance of thickening it I think because there is no continuity of the surface.
You should also only work on half a shell. It lightens the work, and in the end you just have to make a symmetry. It's better to work like this, except when there is a big asymmetry on the model, but it doesn't seem to be the case on a 33 stradale. If the asymmetry is limited to a few details (air intake, boss,...), you'd better deal with them at the end.
Another point where I agree with @Bart, it is perhaps better to treat it in volume. Especially if you want to make reproductions of them. The surface would be good if you limited yourself to design. Keep your work surfaces anyway, and from there extrude a volume to those surfaces. You'll get a gross volume that will be easier to polish on, including all the holidays. At least that's my opinion! I've always found it tedious to sew surfaces back together! And we also end up with trees as long as your arm where it is difficult to find your way around.
Going through the volume will also allow you to make your sliced cuts very easily. Either by the @Bart software or directly on SW.
For your project, is it possible to see the chassis? For fun ! :)