Assembly-to-Order
An assembly-to-order (ATO) product is sold as a parent SKU but assembled only after the order is placed. The parent SKU holds zero or minimal finished goods inventory. Synplex explodes the BOM to understand true component demand so your replenishment planning reflects what needs to be on hand to fulfil incoming orders.
How It Works
When a customer orders an ATO product, no finished goods stock is deducted — because none is held. Assembly begins after the order is placed. Synplex explodes the BOM to attribute demand to each component.
For example, an order for "Custom PC Build" (1 unit) generates component demand of:
- CPU × 1
- RAM × 2
- SSD × 1
- Case × 1
Replenishment planning for each component accounts for both open orders and forecasted future orders, so you always have the right components on hand when builds are due.
Key Difference from Pre-assembly
| Pre-assembly Kit | Assembly-to-Order | |
|---|---|---|
| When is it assembled? | Before the order (batch production) | After the order (per order) |
| What is deducted at sale? | Parent SKU inventory | Nothing yet — components deducted at assembly |
| Finished goods stock held? | Yes | No |
When to Use This Type
Use assembly-to-order when:
- Each unit is built per customer order (personalised or custom)
- Finished goods cannot be held (perishable, fragile, bespoke)
- Assembly is fast enough to fulfil within your lead time promise
- You want to minimise finished goods holding costs
- Components are the items that need replenishment planning
Step-by-Step: Setting Up Assembly-to-Order in Synplex
Step 1: Create the BOM
Navigate to Product BOMs in the main menu and click Create BOM.
| Field | What to enter | Notes |
|---|---|---|
| Parent variant | Search for and select the parent SKU (e.g. "Custom PC Build – Base") | Must be an existing Shopify variant |
| BOM type | Assemble-to-order | Tells Synplex this product is built per order |
| Assembly time | Not required for this type | Leave blank |
| Status | Draft | Activate after adding components |
Step 2: Add Components
Click Select components, then search and select each component. For each component, set the quantity required per unit of the parent SKU.
Example — "Custom PC Build – Base" (1 unit) requires:
- CPU (Intel i5) × 1
- RAM 16GB × 2
- SSD 512GB × 1
- Motherboard × 1
- Case × 1
Step 3: Activate the BOM
Click Activate BOM. Status changes from Draft to Active.
On activation, Synplex:
- Begins attributing parent SKU demand to components
- Updates component forecasts to reflect BOM demand explosion
- Includes demand from this BOM in replenishment recommendations for all components
Step 4: Review Component Replenishment
Once the BOM is active, go to the inventory report or demand plan and review the component SKUs. You should see BOM-driven demand reflected alongside any direct sales demand.
Example for CPU (Intel i5):
| Metric | Value |
|---|---|
| Direct sales demand | 0 (not sold standalone) |
| BOM demand (from Custom PC Build) | 45 units/month |
| Total demand | 45 units/month |
| Stock on hand | 120 units |
| Days of stock | 80 days |
| Replenishment recommendation | Order in 50 days |
| Synplex will flag components that are running low relative to the demand coming through open orders and the demand plan. |
Worked Example
| Setup detail | Value |
|---|---|
| Parent SKU | "Personalised Hamper – Standard" |
| Components | Jam × 2, Chutney × 1, Crackers × 1, Box × 1 |
| Average monthly orders | 80 hampers |
| Current component stock | 200 units each |
| Monthly component demand (from BOM explosion): |
- Jam: 80 × 2 = 160 units/month
- Chutney: 80 × 1 = 80 units/month
- Crackers: 80 × 1 = 80 units/month
- Box: 80 × 1 = 80 units/month
Days of stock at current demand:
- Jam: 200 ÷ 160 × 30 = 37.5 days → Running Low
- Chutney: 200 ÷ 80 × 30 = 75 days → Healthy
- Crackers: 200 ÷ 80 × 30 = 75 days → Healthy
- Box: 200 ÷ 80 × 30 = 75 days → Healthy
Action: Reorder Jam now — it is Running Low.
Typical Examples
- Custom PC builds configured per order
- Personalised gift hampers assembled per order
- Made-to-measure products where each unit differs
- Food & beverage products assembled fresh per order
- B2B orders requiring custom component combinations
Related Pages
Questions? Contact support@synplex.dev