Vessels including an enclosure having an outer perimeter and an interior space, a channel disposed in the interior space, a first port disposed on a surface of the first enclosure at or proximate to a first end of the channel, and a second port disposed on a surface of the first enclosure at or proximate to a second end of the channel, where the channel has a length greater than the shortest distance between the first port and the second port, and where the first port and the second port are in fluid communication with one another. In some cases, the length of the channel is greater than a length of the outer perimeter. Optionally, the vessel may have a second enclosure having an outer perimeter and an interior space with a second channel disposed in the interior space, a third port disposed on a surface of the second enclosure at or proximate to a first end of the second channel, and a fourth port disposed on a surface of the second enclosure at or proximate to a second end of the second channel, where the second port, the third port and fourth port are in fluid communication. In yet some other optional variations, the vessel further includes a plurality of enclosures each having an outer perimeter and an interior space, a channel disposed in the interior space, a port disposed on a surface of the enclosure at or proximate to a first end of the channel, and a port disposed on a surface of the enclosure at or proximate to a second end of the channel, where the channel has a length greater than a shortest distance between the ports, and the second port and the ports disposed on the surface of the plurality of enclosures are in fluid communication. The perimeter shape of the enclosure(s) may be any suitable shape, including, but not limited to, substantially circular, ovate or rectangular.