As each item is a separate product in it's own right, your best option would be to use a configurable product. With configurable products you create one product as the the 'parent' (the configurable product) and then create simple products in addition to this parent product. You then associate the simple products with configurable product.
On the frontend you see a single product - the parent configurable product, and this product has selectable options. Each option you select relates to one of the simple products and on completing the purchase Magento will register a sale, and stock change, against the relevant simple products.
So say you have 2 different options for each product you would create 9 products in total:
- Chimney Liner Kits (parent configurable product)
- Chimney Liner 1 (simple product)
- Chimney Liner 2 (simple product)
- Bottom Connector 1 (simple product)
- Bottom Connector 2 (simple product)
- Chimney Cap 1 (simple product)
- Chimney Cap 2 (simple product)
- Flue Cap 1 (simple product)
- Flue Cap 2 (simple product)
You associate each simple product with the configurable which would result in 4 selectable options for the product on the frontend - Chimney Liner, Bottom Connector, Chimney Cap and Flue Cap. Within each option you would have 2 choices for variation 1 and variation 2. Dependant on how you pick your options, sales would be registered against the relevant simple products.