Lots of people use WooCommerce Bulk Variations to sell products such as personalized clothing, in which customers need to upload artwork or a logo for printing. You can add a file upload field by using WooCommerce Bulk Variations with our other plugin, WooCommerce Product Options. This allows you to create add-on fields which appear underneath the variations grid, and above the add to cart button like this:
With this setup, customers choose the required sizes and colors from the bulk variations grid, and then upload a file underneath. This is all sent to the store owner so that you can fulfil the personalized order.