[3] Through Bock's mediation, Mengelberg received a commission in 1868 to construct a bishop's throne for the Roman Catholic Saint Catherine's Cathedral in Utrecht.

[3] Mengelberg worked closely with Dutch architects Pierre Cuypers and Alfred Tepe, from whom he learnt more about artistic techniques.

In 1869 he became a member of the St. Bemulphus guild founded by Gerardus Wilhelminus van Heukelum, a Utrecht group of Catholic clergy and artists working to bring back the traditions and craftmanship in religious art and architecture.

[5] Mengelberg became the most prominent member of the guild and set up a workshop studio, a closed society of specialized artists employing Gothic principles and techniques to produce items sold to the clergy.

By the late 19th century Mengelberg's studio was employing more than 30 artists, designing and building items for church interiors such as organ fronts, communion pews, pulpits, altars, confessionals, and Stations of the Cross.