How to transfer cost of raw materials to finished goods (which will be charged to cost of sales when items are sold) in quickbooks

I appreciate you for sharing the details of your concern, @janhavi-ppkulkar. I can share some information on how you can 

First, you'll have to set up an inventory for your finished goods.

Then, we can create an expense and make it billable to your customer. Here's how:

1. Click the + New button.
2. Select the transaction (Bill, Expense, or Check) you want to create.
3. Choose the payee.
4. In the Category column, select the expense account for transaction.
5. Enter the description and amount of the expense, then select the Billable checkbox.
6. In the Customer column, select the customer you want to bill for this expense.
7. Once done, select Save and close.

For more information about this process, please refer to this article: Enter billable expenses.

Lastly, you can pull up the journal report from the Reports menu to review the posting of accounts.

In addition, you can also seek self-help video tutorials on our video tutorials for QuickBooks Online to help you get your QuickBooks tasks done in no time.

I'm only a post away if you need more help in completing your other tasks in QuickBooks, janhavi-ppkulkar. Have a great rest of your day!

@janhavi-ppkulkar 

QBO doesn't have the assembly feature. Consider having a 3rd party manufacturing app to integrate with QBO natively.