There are several manufactureres of premade hand in the tank refugiums that have a perforated acrylic 'box' that has a predrilled hole to place a power head in. This is effectively a refugium, but you will see it in your display. Personally I think it is not an eye sore compared with the nitrogen export and 'pod' heaven that you get out of it.
If you are a dIY type, one can easily be made to the exact size you want.