Thanks for coming back to the Community, @mortiz1.
 

I suggest using our Bundle feature in QuickBooks Online (QBO). There you can manage multiple Kits to go together in creating a machine. You'll need to save the Kits in the inventory items before you can create a bundle.
 

Here's how to add inventory items:

1. Go to the Gear icon on the upper right and then select All Lists.
2. On the Lists, hit Products and Services.
3. Click New and then select Inventory.
4. Enter the data needed (Name, Quantity, Date, Cost).
5. Hit Save and close.

You can now include the Kits  in a Bundle, here are the steps:

1. Under Products and Services, click New.
   
2. Choose Bundle (enter the Name and the Kits/items).
   
   
3. Click Save and close.

You can also display bundle components when printing or sending transactions by checking the box.

You can use this video article in managing your inventory: Setting up Inventory in QuickBooks Online. It includes how to enable inventory tracking and how to enter purchase orders: recording, tracking, and more.
 

Should you have questions, leave a query to this thread for further assistance. I'm always here to help you. Enjoy your day and take care!