The easiest way I have found to harvest vinegar eels is to use 100 micron mesh. The finest weave material at spotlight will also go pretty close and is much cheaper. I sandwich the material between some 100mm pipe to create a sieve. This is also useful for artemia.
To harvest you simply pour the culture through the sieve. You can rinse the vinegar off if you want to but I just dip the sieve into the fry tanks. Make sure you return the filtered vinegar solution back to the culture as all the eggs and tiny nematodes that pass through can be collected next harvest when they are bigger.