  A liquid droplet, immersed into a Newtonian fluid, can be propelled solely by
internal flow. In a simple model, this flow is generated by a collection of
point forces, which represent externally actuated devices or model autonomous
swimmers. We work out the general framework to compute the self-propulsion of
the droplet as a function of the actuating forces and their positions within
the droplet. A single point force, F with general orientation and position,
r_0, gives rise to both, translational and rotational motion of the droplet. We
show that the translational mobility is anisotropic and the rotational mobility
can be nonmonotonic as a function of | r_0|, depending on the viscosity
contrast. Due to the linearity of the Stokes equation, superposition can be
used to discuss more complex arrays of point forces. We analyse force dipoles,
such as a stresslet, a simple model of a biflagellate swimmer and a rotlet,
representing a helical swimmer, driven by an external magnetic field. For a
general force distribution with arbitrary high multipole moments the propulsion
properties of the droplet depend only on a few low order multipoles: up to the
quadrupole for translational and up to a special octopole for rotational
motion. The coupled motion of droplet and device is discussed for a few
exemplary cases. We show in particular that a biflagellate swimmer, modeled as
a stresslet, achieves a steady comoving state, where the position of the device
relative to the droplet remains fixed. In fact there are two fixpoints,
symmetric with respect to the center of the droplet. A tiny external force
selects one of them and allows to switch between forward and backward motion.

Fluid Dynamics;Soft Condensed Matter