Fast calculation of the spectrum of a photoionised gas, assuming low optical depth and homogeneous temperatures and densities. Under construction: I plan to add convolution with a Gaussian profile, reddening, and velocity, while keeping the calculation time as short as possible. Currently, if all ions are selected, 1415 emission line fluxes plus hydrogen and helium continua are calculated in <50ms. Plotting takes 50-100ms. See examples: pure hydrogen, hydrogen and helium, NGC 6543, NGC 6326.