  The information contained in the Gaia Second Data Release (DR2) allows to
search for the unusual objects with the pre-selected properties, literally
constructing the stars with the desired characteristics. This work describes
the idea of method, its implementation and the results of searching for the
ultracool compact binaries within 200 parsec distance. The search in the
selected range of absolute magnitudes (M=11..13) has yielded the discovery of
both expected and unexpected objects. We found two cataclysmic variables with
the extreme IR versus UV color index at 126 and 103 parsecs, two eclipsing
pre-cataclysmic systems in the period gap and a candidate young stellar object.
We analyze the new variable stars using the data from synoptic surveys and
compare their properties to the known stars of these types. Applications to the
galactic population density of compact binaries are also discussed.
