I manufacture products and I just want to be able to mark a transaction for materials as an expense but not sure any of the categories listed are appropriate?

Hi there, hello@acrylicbla.

I'm glad you've reached out to us. Let me help and provide some insights on how to categorize the materials in QuickBooks Online.

Are you trying to create an expense transaction with Product and Service? To do this, you'll need to turn on the Show Items table on expense and purchase forms on your QBO account and settings. 

Here's how: 

1. Click the Gear Icon.
2. Go to Account and Settings.
3. Select Expenses.
4. Click Bill and Expenses.
5. Make sure to put a checkmark on the box of the Show Items table on the expense and purchase forms option.
6. Click Save, and Done to apply the changes.

Once done, you can now create an Expense with the Item details. You may want to check this article for additional reference: How to enter, edit, or delete expenses.

To ensure your records are in shipshape, I suggest consulting an accountant before performing the process. They can provide suggestions on how to properly handle the account, especially with the category to use.

In addition, here's an article you can read to learn more about your billable expenses: How to record billable expenses in QuickBooks Online?

If you have any other questions, please let me know in the comments below. I'll be here to lend a hand.

hello@acrylicbla 

QBO doesn't offer any assembly feature. Consider having an additional app to do so.