# POST Create a letter part's colour

Adds a colour to this letter part's colour selection, at the end of its presentation order. The body, the defaults, and the renderability rules are the customiser colours family's, unchanged: `name` is required, a `single` colour needs a `hexcode` and a `multi` or `flow` colour needs `multi_colour_hexcodes` (422 `colour_value_required`), and the `custom_texture` finish is refused until image upload ships. The letter part must already have a colour selection — create one through the letter-part routes first. Requires `customisers:write` and an `Idempotency-Key`. The write clears the customiser's cached storefront configuration and runs the advisory language sync. It never regenerates Shopify products, product images, or the product cache. Option writes also spend one unit of a separate per-key option-write budget.

- Source URL: https://www.signcustomiser.com/help/api/v3-post-create-a-letter-part-s-colour/
- Markdown URL: https://www.signcustomiser.com/help/api/v3-post-create-a-letter-part-s-colour.md
- Group: Customiser letter parts
- Method: POST
- Path: /api/v3/customisers/{customiser_id}/letter-types/{letter_type_id}/letter-parts/{letter_part}/colours
- Auth: Bearer token
- Required scopes: `customisers:write`

## Path parameters

- customiser_id (string, required): The customiser id. Example: 1
- letter_type_id (string, required): The letter type id. Example: 7
- letter_part (string, required): The letter part. Example: face

## Body parameters

- colour_type (string, optional): No description provided.
- texture (string, optional): No description provided.
- min_size_rule (string, optional): No description provided.
- price_multiplier_target (string, optional): No description provided.
- name (string, optional): No description provided.
- description (string, optional): No description provided.
- hexcode (string, optional): No description provided.
- multi_colour_hexcodes (array, optional): No description provided.
- base_price (integer, optional): No description provided.
- price_multiplier (number, optional): No description provided.

## Request body example

```json
{
  "colour_type": "single",
  "texture": "flat",
  "min_size_rule": "any",
  "price_multiplier_target": "base_letter_price",
  "name": "Warm White",
  "description": "Our warmest white",
  "hexcode": "#FFEEDD",
  "multi_colour_hexcodes": [
    "#FF0000",
    "#00FF00"
  ],
  "base_price": 500,
  "price_multiplier": 1.2
}
```

## cURL example

```bash
curl https://web.signcustomiser.com/api/v3/customisers/1/letter-types/7/letter-parts/face/colours \
  --request POST \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer YOUR_API_TOKEN' \
  --header 'Content-Type: application/json' \
  --data '{
  "colour_type": "single",
  "texture": "flat",
  "min_size_rule": "any",
  "price_multiplier_target": "base_letter_price",
  "name": "Warm White",
  "description": "Our warmest white",
  "hexcode": "#FFEEDD",
  "multi_colour_hexcodes": [
    "#FF0000",
    "#00FF00"
  ],
  "base_price": 500,
  "price_multiplier": 1.2
}'
```

## Response examples

### 201 POST 201 example 1

```json
{
  "data": {
    "object": "colour",
    "id": 31,
    "customiser_id": 42,
    "name": "Warm White",
    "description": null,
    "colour_type": "single",
    "hexcode": "#FFEEDD",
    "multi_colour_hexcodes": null,
    "texture": "flat",
    "min_width_cm": null,
    "min_height_cm": null,
    "min_size_rule": "any",
    "base_price": 0,
    "currency": "USD",
    "price_multiplier": 1,
    "price_multiplier_target": "base_letter_price",
    "sort_order": 1,
    "image_url": null,
    "example_image_url": null,
    "texture_image_url": null,
    "created_at": "2026-08-13T00:00:00Z",
    "updated_at": "2026-08-13T00:00:00Z"
  },
  "links": {
    "self": "https://web.signcustomiser.com/api/v3/customisers/42/letter-types/7/letter-parts/face/colours/31",
    "documentation": "https://www.signcustomiser.com/help/api/"
  },
  "meta": {
    "api_version": "v3",
    "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
  }
}
```

### 400 Missing idempotency key

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/missing_idempotency_key",
  "title": "Missing idempotency key",
  "status": 400,
  "code": "missing_idempotency_key",
  "detail": "Provide an Idempotency-Key header for this write.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 401 Missing API key

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/missing_api_key",
  "title": "Missing API key",
  "status": 401,
  "code": "missing_api_key",
  "detail": "Provide a store API key as a bearer token.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 403 Insufficient scope

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/insufficient_scope",
  "title": "Insufficient scope",
  "status": 403,
  "code": "insufficient_scope",
  "detail": "This operation requires the customisers:write scope.",
  "required_scopes": [
    "customisers:write"
  ],
  "granted_scopes": [
    "customisers:read"
  ],
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 404 Unknown letter part

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/resource_not_found",
  "title": "Resource not found",
  "status": 404,
  "code": "resource_not_found",
  "detail": "The requested resource does not exist or does not belong to the authenticated store.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 409 Idempotency conflict

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/idempotency_key_conflict",
  "title": "Idempotency key conflict",
  "status": 409,
  "code": "idempotency_key_conflict",
  "detail": "This Idempotency-Key was already used for a different request body on this operation.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 413 Request body too large

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/request_too_large",
  "title": "Request too large",
  "status": 413,
  "code": "request_too_large",
  "detail": "The request body must not exceed 2 MiB.",
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 422 Unknown field

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/unknown_field",
  "title": "Unknown field",
  "status": 422,
  "code": "unknown_field",
  "detail": "The request contains fields this operation does not define: /colour.",
  "errors": [
    {
      "pointer": "/colour",
      "code": "unknown_field",
      "detail": "The field \"colour\" is not supported by this operation."
    }
  ],
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```

### 429 Option write budget exhausted

```json
{
  "type": "https://www.signcustomiser.com/help/api/problems/rate_limited",
  "title": "Too many requests",
  "status": 429,
  "code": "rate_limited",
  "detail": "You have exceeded the request limit for this API key.",
  "retry_after": 37,
  "request_id": "req_01jz9x2k7c8f3m5n6p7q8r9s0t"
}
```