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We present two new tools for studying and modelling metal absorption lines inthe circumgalactic medium. The first tool, dubbed ``NMF Profile Maker''(NMF$-$PM), uses a non-negative matrix factorization (NMF) method and providesa robust means to generate large libraries of realistic metal absorptionprofiles. The method is trained and tested on 650 unsaturated metal absorbersin the redshift interval $z=0.9-4.2$ with column densities between $11.2 \le\log{(\mathrm{N/cm^{-2}})} \le 16.3$, obtained from high-resolution ($R> 4000$)and high signal-to-noise ratio ($S/N \ge 10$) quasar spectroscopy. To avoidspurious features, we train on infinite $S/N$ Voigt models of the observed lineprofiles derived using the code ``Monte-Carlo Absorption Line Fitter''(MC$-$ALF), a novel automatic Bayesian fitting code that is the second tool wepresent in this work. MC$-$ALF is a Monte Carlo code based on nested samplingthat, without the need for any prior guess or human intervention, can decomposemetal lines into individual Voigt components. Both MC$-$ALF and NMF$-$PM aremade publicly available to allow the community to produce large libraries ofsynthetic metal profiles and to reconstruct Voigt models of absorption lines inan automatic fashion. Both tools contribute to the scientific effort ofsimulating and analysing metal absorbers in very large spectroscopic surveys ofquasars like the ongoing Dark Energy Spectroscopic Instrument (DESI), the4-meter Multi-Object Spectroscopic Telescope (4MOST), and the WHT Enhanced AreaVelocity Explorer (WEAVE) surveys.

Towards an automatic approach to modelling the circumgalactic medium: new tools for mock making and fitting of metal profiles in large surveys