CLUMP is a collection of scripts to generate multi-sphere particles of overlapping or non-overlapping spheres, which approximate target geometries. Multi-spheres (a.k.a. clumps) are popular in numerical simulations using the Discrete Element Method (DEM), but these geometric object can find applications in a wider perspective, past numerical modelling. The motivation behind developing CLUMP stemmed from the need to compare different clump-generation techniques, both in terms of particle morphology and mechanical performance using the DEM. To this end, CLUMP offers two existing and well established clump-generation techniques and proposes a new one. The generated clumps can be exported in various formats, compatible with some of the most prominent DEM codes. Last, the surface of each generated clump can be extracted as a triangulated mesh and saved as an stl file, allowing for a full characterisation of particle morphology, using tools like SHAPE or 3D-printing of physical particle replicas. CLUMP was initially developed in MATLAB and has now been fully translated in Python. Both implementations will continue to be developed in parallel as the software evolves.