Shopify Custom Functionality

I am looking for a Shopify expert who can create custom functionality for my online store. Specifically, I need customization of customers' product quantity. I have a rough idea of how I want the design and layout to look, but I am open to suggestions. My top priority is optimizing user experience on my site. The ideal freelancer should have experience with Shopify theme development and custom functionality, as well as a strong understanding metaobjects, metafields, and manipulation of Shopify functionality via the use of their values.

You must to be available to work on this immediately. Compensation will be negotiated once you understand the full requirements.