DES3D (Dynamic Earth Solver in Three Dimensions) is a flexible, open-source finite element solver that models momentum balance and heat transfer in elasto-visco-plastic material in the Lagrangian form using unstructured meshes. It provides a modeling platform for long-term tectonics as well as various problems in civil and geotechnical engineering. On top of the OpenMP multi-thread parallelism, DES3D has recently adopted CUDA for GPU computing. The CUDA-enabled version shows speedup of two to three orders of magnitude compared to the single-thread performance, making high-resolution 3D models affordable. This clinic will provide an introduction to DynEarthSol3D’s features and capabilities and hands-on tutorials to help beginners start using the code for simple tectonic scenarios. Impact of the two types of parallelization on performance will be demonstrated as well.