  We report on a new versatile transportable endstation for controlled molecule
(eCOMO) experiments providing a combination of molecular beam purification by
electrostatic deflection and simultaneous ion and electron detection using
velocity-map imaging (VMI). The $b$-type electrostatic deflector provides
spatial dispersion of species based on their effective-dipole-moment-to-mass
ratio. This enables selective investigation of molecular rotational quantum
states, conformers, and molecular clusters. Furthermore, the double-sided VMI
spectrometer equipped with two high-temporal-resolution event-driven Timepix3
cameras provides detection of all generated ions independently of their
mass-over-charge ratio and electrons. To demonstrate the potential of this
novel apparatus, we present experimental results from our investigation of
carbonyl sulfide (OCS) after ionization. Specifically, we provide the
characterization of the molecular beam, electrostatic deflector, and electron-
and ion-VMI spectrometer. The eCOMO endstation delivers a platform for
ultrafast dynamics studies using a wide range of light sources from table-top
lasers to free-electron-laser and synchrotron-radiation facilities. This makes
it suitable for research activities spanning from atomic, molecular, and
cluster physics, over energy science and chemistry, to structural biology.
