  The vast majority of star-forming galaxies are surrounded by large reservoirs
of gas ejected from the interstellar medium. Ultraviolet absorption and
emission lines represent powerful diagnostics to constrain the cool phase of
these outflows, through resonant transitions of hydrogen and metal ions. The
interpretation of these observations is often remarkably difficult as it
requires detailed modelling of the propagation of the continuum and emission
lines in the gas. To this aim, we present a large public grid of about 20000
simulated spectra which includes HI Lyman-alpha (Lya) and five metal
transitions associated with MgII, CII, SiII, and FeII that is accessible online
at https://rascas.univ-lyon1.fr/app/idealised_models_grid/. The spectra have
been computed with the RASCAS radiative transfer code for 5760 idealised
spherical configurations surrounding a central point source emission, and
characterised by their column density, Doppler parameter, dust opacity, wind
velocity, as well as various density/velocity gradients. Designed to interpret
Lya and metal line profiles, our grid exhibits a wide diversity of resonant
absorption and emission features, as well as fluorescent lines. We illustrate
how it can help better constrain wind properties by performing a joint
modelling of observed Lya, CII, and SiII spectra. Using CLOUDY simulations and
virial scaling relations, we show that Lya is expected to be a faithful tracer
of the gas at T=10^4-10^5 K, even if the medium is highly-ionised. While CII is
found to probe the same range of temperatures as Lya, other metal lines merely
trace cooler phases (T=10^4 K). As their gas opacity strongly depends on gas
temperature, incident radiation field, metallicity and dust depletion, we
caution that optically thin metal lines do not necessarily originate from low
HI column densities and may not accurately probe Lyman continuum leakage.
