Sell the sets your variants can't: a holder plus any three of 27 liner colours, a tea sampler, a sock trio. Customers pick each part on the product page, from a product's variants or a whole collection. Every part enters the cart as the real product, so stock per colour stays exact. The set discount applies only once every part is in the cart. Remove one and it is gone. Code gifts: a creator shares a code, the gift adds itself to the cart, and a real Shopify discount code covers it.

• Customers pick each part of a set from the colours and products you sell
• Every part enters the cart as the real product, so stock per colour stays exact
• Set discount by percent, amount or set total, only once the set is complete
• Code gifts: a creator's code adds the gift to the cart by itself
• One toggle in the theme editor. No theme code, no calls to outside servers