How best to set up complex store

Thank you for all your help getting my first store up and working.

Now to the next - which is a site selling technical fittings!

From the attached sample you will see my problem - in total there are approx 200 products (ie CF SILVER PLATED COPPER GASKETS - OFHC) split into 3 product sections - each product has approx 8 size options with different part number and price etc.

Should I set up the 3 sections as categories with each product name (ie CF SILVER PLATED COPPER GASKETS - OFHC) set up as a sub category, and each part number set up as a individual product.

I want to be clear from the start as it would be easy to waste a awful lot of time and effort and it needs to be presented to the user in a logical and easy to navigate way.

Any tips, examples or experience for this kind of site appreciated.

Many thanks in advance.

here is a example of the products - sorry I thought I sent it with the last post

OK lets try again