This is a guide on how to have build parts that are placed by using an item instead of using the blueprint item to place them.
Start by going to the ItemList and create a new item by clicking the + button like shown in the video below.
Then go though and set the details for the item, for this guide I will be creating an item for the wood foundation. Start by setting the Row Name to the same Row Name of the build part you want to place from the Build Part List. For example the Build part Row Name for the wood foundation is Foundation_Wood so the Row Name of the item in the ItemList for the wood foundation must be Foundation_Wood. Below is an image with the row name highlighted.
Below you can see the Row Names highlighted in the Build Part List so you can find the Row Name of the items that you create.
This guide wont go in to filling out all details in the ItemList as there is no difference for most of the item setting for building items, but the one other setting you need to set for building placement items is the Category must be set to Building. Below is an image of all the ItemList setting for the example wood foundation item.
Next go to the BuildPartList and select the build part that you item is going to place so for me thats the Foundation_Wood then find the Building Cost and change the Item 1 row name to the Item we created early from the ItemList. So for this guide it would be the Foundation_Wood item. Then set the Item 1 Count to 1 like the image below.