Build-a-Box lets your customers create their own product bundle by choosing items from a list you curate. They pick the required number of items (for example, 3 or 6). Once the box is complete, Subi automatically applies the price or discount you set.
What Build-a-Box supports
You can sell a Build-a-Box as:
A one-time purchase
A subscription (a recurring box)
Both, so the customer chooses at checkout
And you can price it in two ways, set in the Box structure section of the plan editor:
Fixed price: one set price for the whole box, no matter which items the customer picks.
Discount: a percentage or fixed amount off the total of the items the customer picks.
The next section explains both in detail.
How box pricing works
Every Build-a-Box uses one of two pricing models, chosen in the Box structure section of the plan editor. Each box size can have its own price or discount.
Fixed price
You set one price for the box, for example "$40 for any 6 items". The customer always pays that price, whatever they put in the box. This is ideal for curated boxes where you want a clean, predictable price.
Discount
The box price is the total of the chosen items, minus a discount you set, and it updates as the customer adds items. You can set the discount as:
Percentage: a percentage off the total of the chosen items, applied across all items in the box.
Fixed amount: a set amount off the box, distributed across the items (so it doesn't appear as a single discount line at checkout).
How the price is calculated
Pricing applies per box, not per cart. Each box is priced on its own.
A customer can add more than one box to the same cart, and each box keeps its own price.
When the box price applies
The box price (or discount) is applied only when all of these are true:
All items belong to the same box size
The whole box is either one-time or subscription, not a mix
The box has exactly the required number of items
Every item comes from the box's product pool
Subscription discounts
When a box is both discounted and subscribed, Subi applies the discounts in sequence rather than adding them together:
Build-a-Box discount
Subscription discount
Who should use Build-a-Box?
For merchants
Use Build-a-Box to offer custom product bundles, subscription boxes, or flexible promotional kits.
For customers
Customers can build their own product box from a curated list and subscribe to recurring bundles.
Step 1: Create a Build-a-Box plan in Subi
Go to your Subi dashboard.
Open Plans (the Subscription Plans page).
Click Create plan.
Select Build a box.
Then fill in the plan settings below.
Plan details
Plan title: the name of the bundle.
Plan description: an internal or display description.
Product pool
Choose which products customers can pick from. You can add products in two ways:
By collection: select a collection to include all of its products.
Manual selection: choose specific products individually.
Customers can only choose products from this pool.
Box sizes
Define how many items customers must select for each box size (for example, a box of 3 items or a box of 6 items).
Customers must select exactly this number of items before they can add the box to their cart.
Box structure & pricing
Choose how the box is priced under Box structure:
Fixed price: set one price for each box size.
Discount: choose Percentage or Fixed amount, then set the discount for each box size.
Each box size can have its own price or discount.
If you change the Box structure of an existing plan, the prices or discounts you entered are cleared so you can re-enter them under the new model. Your box-size names and item quantities are kept. See Troubleshooting below.
Subscription settings
If you let customers subscribe, set the subscription frequency and any subscription discount rules. This step is required when subscription purchase is enabled.
Purchase type
Choose how customers can buy: one-time, subscription, or both.
Save the plan
After you save, Subi generates a Box ID. You'll need this ID to display the widget on your storefront.
Step 2: Add the Build-a-Box widget to your store
Creating the plan does not automatically show it on your store. You add the widget yourself.
Copy the Box ID from Subi.
In your Shopify admin, go to Online Store → Themes.
Click Edit theme.
Navigate to the section where you want the widget.
Click Add block.
Select Apps.
Click Build box widget (Subi Subscriptions).
In the right-side panel, enter the Box ID.
Click Save.
What customers see
On your storefront, customers will:
Open the Build-a-Box section
Select a box size
Choose one-time or subscribe, and a frequency
Choose products from the available pool
Add items until the required quantity is reached
Add the box to cart
How the price appears
The widget always shows one clear price, the price the customer actually pays:
Fixed-price box: the customer sees just your set price.
A box with a saving (a discount, or a subscription discount): the customer sees the original price struck through and a single "Save X%" (or "Subscribe & Save X%") label.
The full breakdown (box discount, subscription discount) is tucked behind a Details link, so the default view stays clean.
A fixed-price box, one-time, shows just the set price:
A box with a saving shows a clean headline price with "Subscribe & Save" and a Details link:
The same box with Details expanded, so the full breakdown is one tap away:
Early access: product filters and grouped variants
We're piloting two ways to make a large Build-a-Box easier to shop. Both are part of an Early Access Program: they're switched on for a limited group of stores while we gather feedback, and you can ask to join (see How to join the Early Access Program below).
Product filters
When your box draws from a large product pool, you can let customers narrow the list by tapping filter chips. Each filter has a name you choose (for example, "Material" or "Type") and is built from one or more of your Shopify collections.
Customers tap a chip to show only the products in that collection, then tap it again (or tap Clear all) to return to the full list. You can add more than one filter so customers can combine them.
You set filters up in the Filters section of the Build-a-Box plan editor:
Click Add filter.
Enter a Label for the chip. This is the text customers tap, for example “Material” or “Type”.
Under Collections, click Browse and choose the collection (or collections) the filter should match.
Repeat to add more filters, then Save.
Filters are set up when you edit an existing box, not while you create it. Create your Build-a-Box plan and save it first, then open it again to add your filters.
Grouped product variants
When a product comes in several variants (for example, the same item in five colours), the widget shows it as a single product card with a variant picker instead of a separate card for every variant. Customers pick the variant they want on the card, then add it to the box.
This keeps the product list short and easy to scan, even for catalogs with lots of variants. Grouping turns on automatically for products that have variants, so there's nothing extra to set up.
How to join the Early Access Program
These features aren't switched on for every store yet. To try them on your store, reach out to our team and ask to join the Build-a-Box early access program:
Live chat: available in Subi or on our website.
Email: [email protected]
We'll enable it for your store and help you set up your first filters.
Troubleshooting
The Build-a-Box widget isn't showing
Check that:
The widget block is added to the theme
The correct Box ID is entered
Theme changes are saved
The most common cause is a missing or incorrect Box ID.
My prices disappeared after I changed the Box structure
This is expected. When you switch an existing plan between Fixed price and Discount, the amounts are cleared because a price and a discount are not the same thing (a "15% discount" can't be safely reused as a "$15 price"). Your box-size names and item quantities are kept.
To finish the switch, enter a price (or discount) for every box size, then Save. Saving is blocked until every box size has a value.
The price looks different from what I expected
Fixed-price boxes show one clean price (your set amount) with no discount breakdown by default.
Discounted boxes show the price with a "Save X%" label; tap Details to see the box discount and subscription discount separately.
Subscription discounts are applied in sequence (after the box discount), which affects the final price.
Need help?
Live chat: available in Subi or on our website.
Email: [email protected]