The phrase "a functional piece of" is correct and usable in written English.
It can be used to describe an item or component that serves a practical purpose or function within a larger context.
Example: "The new software update includes a functional piece of code that improves system performance."
Alternatives: "a practical component of" or "a useful element of".
On the one hand, it's a functional piece of design; on the other, it is a sublime piece of sculpture.
He said he saw the building summit as "a functional piece of sculpture, a piece of civic art of an unusual scale".
By painting it matte silver, he turned it into a functional piece of filigree jewelry set against the dark brick walls.
But he added, "If you are looking for a functional piece of furniture, you may not want to see rough screws".
It has enhanced the garden, where workshops and festivals are held, because "it's a functional piece of art," said Sebert Harper, an environment educator for the Phipps development corporation.
What looks like a functional piece of plastic has been studied as a modern extension of the male hunter/gatherer role and as a potent symbol of male oppression - with batteries.
It's a purely functional piece of architecture made fantastical by its epic scale.
That could make Pencil a more functional piece of hardware for those who already own it, while potentially exposing it to a wider range of folks who use third-party applications and just want a better stylus.
What we've done is created a very reduced but highly functional piece of hardware that listens to neurons in the spinal cord and gives you feedback that allows you to individually control those neurons.
Over the ensuing decades this functional piece of sportswear kit migrated off the courts to become a symbol of sophisticated sporting style.
Bristol Rugby club's strength and conditioning coach, Dave Bell, describes the TRX system as "the most effective and functional piece of equipment I've seen for years".
