A process for producing a tube suitable for microfluidic devices. In one embodiment, at least one channel having a wettable surface is created that allows liquid metal to flow into a measuring reservoir without the liquid metal being pressurized and without applying other external forces on the liquid metal to facilitate its movement. The ring and the salt solution are disposed within the outer body such that a portion of the first right torsion field propagates through the salt solution. The wall bracket includes a bottle retainer for holding a bottle having a pump. The storage slots store the glass offcuts at a substantially vertical position of less than 90 degrees with reference to the horizontal.