I am wanting to offer our customers a free gift with purchase but in a specific design so for example if they buy x design they receive the free product in x design but if they buy z design they will receive the free product in z design.
Welcome to the Shopify Community! This is definitely possible with Shopify, and there are a couple ways you could set it up. I wrote a very detailed post about creating Buy X Get Y promotions that I recommend reading through. It outlines your two main options for what you are looking to achieve, which are either set it up using the discount feature available in the Shopify admin, or set it up using an app from the Shopify app store.
Once you've read through my post, you'll see that when using the discount feature available through the Shopify admin, you can select which products or collections each promotion applies to. Therefore, you could set up a different discount for each design.
Note: you can only have one active automatic discount at a time through the Shopify discount feature, which means you would need to set these up as discount codes. This means the customer will need to enter the discount code at checkout in order to receive the promotion.
It may be smoother for your customer experience to use an app from the app store that automatically adds a free gift to your customers cart when they qualify for the promotion. However, this will be up to you and your business needs.
Let me know if you have any further questions, or if you have any troubles setting this up. Happy to help!
Hilary | Community Moderator @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog