While you are not able to directly copy a BOM from one Tech Pack to another, there are two ways to simplify the process of creating a BOM. They are the following:
Create a BOM Template
From the Global Navigation, click on BOM Template Library
Click the Add Icon in the bottom right corner
From there you can create a BOM template for any product style. (See Also: Creating BOM Templates)
To add the BOM Template to a New Product record, from the Bill of Materials section of the Product Record, click the Overflow icon in the upper right hand corner of the BOM, and select "Import Template"
Next, click on the BOM template you created
Proceed to change or update any other information accordingly.
Note: Colorway and Variant information will not be included in the BOM Template, so this has to be manually entered.
Copy a Product
From the Product Library, select the Product you wish to Copy the BOM from
Click the Overflow icon and select Copy
The Product copy will appear with the (Copy) at the end of the Product name
From there, you can change the BOM based on the criteria of the new Product.