Build-A-Box lets shoppers fill their own subscription box with the products you choose. It comes with the Business plan and higher. Open it from the app menu: Create and Manage lists your boxes.

Dynamic Pricing Bundle charges for each product the shopper picks. Fixed Pricing Bundle charges one price for any mix, and has its own guide next to that option. Allow One-time Purchase lets shoppers buy the box without subscribing.

Under Subscription Plans, pick the plans with the products shoppers can choose from. If you pick more than one plan, they need the same delivery frequencies.

Tiered discounts reward bigger boxes, by number of products or by order amount, on top of the plan's own discount.

Choose Enabled under Build-A-Box Status. Your box only gets its link when it's enabled.

Advanced Settings set the fewest and the most products a box can hold, Unique Product Check (counts only different products, and needs Build a box validation in your Shopify checkout settings), a minimum order amount, and where shoppers go when the box is ready: the cart, checkout, another box or a page you choose. Show Advanced Settings changes the button label and the choose-products text, and adds your own HTML above or below the box.

After you save, Copy Link gives you your box's address. Add it to your store's menu so shoppers can find it.

To let customers edit what's in their box from the customer portal, turn on Let customers adjust quantities in their product bundles (Customer Portal) in the Configuration tab. The Labels, Custom CSS and Custom Snippets tabs change the box page's text, its style and where it shows on your store.