Build into
Definition 1 of 3
Pro Tip 1/3Design Centric
Used to describe features that are an integral part of a product's design to serve a function. 
The software has security features built into its architecture.
Pro Tip 2/3Seamless Integration
Indicates that the feature is blended so well into the design that it appears natural or unnoticeable. 
The phone's speaker is built into the screen seamlessly.
Pro Tip 3/3Non-Additive
Suggests that the item isn't just added on, but rather included in the original structure or design. 
The bookshelf was built into the wall, not attached later.