Duane Denver Mass, 68, of Oklahoma City and Tulsa, died in Oklahoma City on Sunday, December 7, 2025.

He was born in Coffeyville, Kansas in 1957 to Frank and Laura Imogene Mass, and was raised on a family ranch in Hartshorne, Oklahoma. Duane worked as a carpenter before attending Oklahoma State University to study architecture. He founded Mass Architects in 1995, focusing his work on building community-oriented projects for Oklahoma's county health departments, multiple Oklahoma school districts, airports, Catholic Charities of the Archdiocese of Oklahoma City, The Education and Employment Ministry, and by working as the Capitol Architect for the renovation of the Oklahoma State Capitol building.

Duane was preceded in death by his parents Frank and Laura Imogene Mass, and is survived by his wife Robin, their children Frank Mass and wife Lauren and their daughter Vivian, Jessica Douglas and husband Collin, and Rachel Mass. He is also survived by his daughter Natalie and his siblings Mickey Switzer, Roger Mass, Lannette Huskey, Susan Evans, and Frankie Mass.

Services will be held at Christ the King Catholic Church in Oklahoma City at 10:30 am on Monday, December 15th.  Additional services will be held in Hartshorne, Oklahoma.  Rosary will be Tuesday, December 16th, at 7:00 p.m. at the Holy Rosary Catholic Church in Hartshorne.  Mass will be held on Wednesday, December 17th, at 10:30 at the Holy Rosary Catholic Church in Hartshorne.  Burial will follow at Holy Rosary Cemetery in Hartshorne.

Contributions may be made to the Glioblastoma Foundation at glioblastomafoundation.org in Duane's honor.