Custom Collection
This is a page using a custom template (easy to make/modify) to display collections in a sortable order. The custom page template utilizes a Shopify menu (each item linking to a collection) so that you can sort them, however, when the code resolves on the page, it is a list of collections. Using CSS selectors, it is pretty easy to modify the look/feel.
You can make unlimited menus, thus you can make ulimited custom collections.