  Insulating uniaxial room-temperature ferromagnets are a prerequisite for
commonplace spin wave-based devices, the obstacle in contemporary ferromagnets
being the coupling of ferromagnetism with large conductivity. We show that the
uniaxial $A^{1+2x}$Ti$^{4+}$$_{1-x}$O$_3$ (ATO), $A=$Ni$^{2+}$,Co$^{2+}$ and
$0.6<x \leq 1$, thin films are electrically insulating ferromagnets already at
room-temperature. The octahedra network of the ATO and ilmenite structures are
similar yet different octahedra-filling proved to be a route to switch from the
antiferromagnetic to ferromagnetic regime. Octahedra can continuously be filled
up to $x=1$, or vacated $(-0.24<x<0)$ in the ATO structure. TiO-layers, which
separate the ferromagnetic (Ni,Co)O-layers and intermediate the
antiferromagnetic coupling between the ferromagnetic layers in the NiTiO$_3$
and CoTiO$_3$ ilmenites, can continuously be replaced by (Ni,Co)O-layers to
convert the ATO-films to ferromagnetic insulator with abundant direct cation
interactions.
