Complete playroom project including toyboxes, bookcases, and a built-in desk (for two quickly growing boys).
The client--who I had built a custom entertainment center for in the same home previously--contact me about a year later, wanting to add some kind of storage in her playroom.
We met and I sized up the layout and recommended toy boxes under the windows that would also double as a window seat (with cushions) and the bookcase towers flanking a simple desk--with a map of the world framed above the work space.
I designed the toy boxes to be re-usable later as ottomans or side / occasional tables (they are finished on all four sides and free standing) once the boys are grown and the toys are gone.
This design allows all of the pieces to be easily removed and taken with the family if they ever move--so in this respect they are more like furniture than built-ins.