  Using lattice homology, we give an explicit combinatorial description of the
Seiberg-Witten-Floer spectrum $\mathit{SWF}(Y)$ for $Y$ an almost-rational
plumbed homology sphere. This class of manifolds includes all Seifert fibered
rational homology spheres with base orbifold $S^2$. Using our computations, we
provide a calculation of Manolescu's $\kappa$-invariant for certain connected
sums of these spaces.
