PoW! is an algorithm – an algorithm that grabs a single Bitcoin transaction as it passes through the Blockchain and moulds the data into a tangible shape that doesn't physically exist.
If a Bitcoin is itself a 'proof-of-work', a piece of data which is difficult (costly and time-consuming) to produce but easy for others to verify, that then makes each inclination of PoW! a proof-of-work of a proof-of-work – by taking the result of a 'proof-of-work' from the Blockchain, the algorithm behind PoW! passes a 3D model to a rendering application which has to work hard to produce what we can easily see.