A collection of different studies about bound states of hadrons composed of charm quarks is presented. These studies used a symmetry preserving vector-vector contact interaction model within the framework of Schwinger-Dyson and Bethe-Salpeter equations. Despite its limitations, the contact interaction model offers a simple-to-implement alternative to perform exploratory
studies of QCD, obtaining an spectrum of charmed hadrons in agreement within 2% when they are compared with experimental data. In particular, the spectrum of charm and beauty mesons is presented.