Planning: Building around Ikea shelves

Here's a clean, modern space with a built-in bookcase.

[Tribe Studio Architects via Desire to Inspire]

[Tribe Studio Architects via Desire to Inspire]

I don't know if it's the case here, but the black wall shelves could be store-bought components that are mounted and trimmed to become built-ins.  You would just have to plan the space and dimension everything according to what is available at the store.  A case of 'cart before the horse' that actually saves time and money.