One way to make microfluidic devices, is to use a milling machine. A paper by Ali Lashkaripour, Ryan Silva and Douglas Densmore compares three micromilling machines (tiny milling machines), evaluated their accuracy, and provides methods for evaluating the accuracy of your own miromilling machines.
The only machine evaluated that is still being produced, is the Carbide 3D’s Nomad 883, at just $2400. The discontinued OtherMill Pro and V2, which are discussed in the paper, have been replaced by the Bantem PCB milling machine which costs $3200.
EDIT: Ali Lashkaripour says:
we found that the Nomad machines have a higher X-Y accuracy, however, the Othermill machines (rebranded as Bantam Tools ) are more suitable for microfluidic fabrication because of the auto-locating feature and a higher spindle-speed.
For simple microfluidic chambers, we’ve covered making microfluidic devices via parafilm and a knife printer. For more complex microfludic devices we often use milling machines, so we appreciate the well though out study on micromilling accuracy.