Funny shaped tank...funny shape filter

A friend is getting a tank built. It will act as a coffee table.

30 inches high, 3 foot square.
It will sit on a six inch wooden plinth, with access to the space underneath
the tank.

He wants to hide all the filtration system within the plinth.

So he needs a thin system (6 inches high) that will extract, filter, heat
and pump back the clean water.

Does anyone know of one that is commercially available. He wants to avoid
building his own one.

Thanks in advance.