The methodology of his artistic practice is polyhedral and is nourished by carrying out in-house research projects that combine sociology and visualization. From a socio-aesthetic commitment, Vallecillo highlights a multiplicity of strategies that enhance and redefine the materials, actions and objects used in his works. He has participated in dozens of collective and individual exhibitions in America, Europe and Asia.

He has also participated in international Biennials such as: Cuenca, Ecuador 2022, FEMSA Biennial, Mexico 2020, Cuenca 2016, Mercosur 2015, Montevideo, 2014, Venice 2011, Central American 2010, Havana 2009.

He has participated in residences such as: Flora Ars + natura Bogotá 2018, LARA Panamá 2017, Beta Local, San Juan, Puerto Rico 2016, illy SustainArt, Venice, Italy, 2013 World Award, among others. His work can be found in the following collections: Phoenix Art Museum, Arizona, Bronx Museum, New York, Daros Latin America, Zurich, CIFO, Miami, Florida, Sayago and Pardón, Los Angeles, CA, Teorética, San José, Costa Rica, Patricia Phelps de Cisneros Collection, New York- Caracas, MoLaa Museum of Latin American Art, California, Museum of Contemporary Art and Design, San José, Costa Rica, Saxo Bank, Denmark, LARA, Singapore, among others.

Adán received the Mid-Career Artists Award 2020 from CIFO, USA.