I have a shop selling safety clothing. One such piece of equipment are safety gloves which come in 3 different sizes and 3 different colours. Each combination of size and colour has its own part number, price does not change. So, to have magento working the combinations as it should, do I create two attributes, glovesize and glovecolour enter their attributes and apply it to a configurable product?
Or, do I just add the custom options to the Safety Gloves product?
You can do it both ways. The difference is that you can use attributes when adding any product (provided they are included in the attribute set you selected), while custom options are created per product. Another difference is that each product combination in a configurable product has a separate inventory, while combinations that are created with custom products share the same inventory.
Product Matrix extension makes creation and management of configurable products much simpler. The extension enables Admin to create and edit configurable products with TWO attributes in a convenient matrix form, where Admin can specify configuration for each simple associated product. It creates a matrix where Admin can specify simple associated product’s configuration: name, price, SKU, weight, availability, quantity, visibility and status. This is a must-have extension that will save you a lot of time and effort.
If you have product which comes in variation - size and color, those variations can be created either by means of simple products with custom options or using configurable products.
Custom options are easier to create but they do not allow to track inventory of each variation. Here is the article with detailed comparison of custom options and configurable products.