Optical pumping on the 2$^3$S--2$^3$P transition (1083 nm) of metastable $^3$He or $^4$He atoms is used for science and applications. Gas is usually enclosed in elongated cells with lengths ranging from several centimeters to several meters for efficient absorption. Good magnetic-field homogeneity is needed for weak diffusion-induced relaxation and long NMR signal lifetimes. A compact coil system is designed using a target-oriented numerical optimisation method. It provides a suitably uniform field over cell volumes, with characteristics depending on chosen optimisation parameters. Additional pairs of coils can be used to generate transverse field components with contributions to total field inhomogeneities that are discussed.