Numerical simulations of physical phenomena can be computed by many (commercial/free) software packages, but despite the apparent variety, all of them rely on a relatively small set of operations during the preparation, exploitation, and post-processing of these simulations, e.g., handling and modifying meshes and fields. Muscat is a Python library designed to address these supporting tasks. It features an efficient data model for meshes and field objects, as well as input/output routines compatible with various formats. A finite element engine allows to assemble abstract variational formulations and integrate fields on volumes and surfaces. Muscat is actively used in artificial intelligence and model order reduction [1, 2, 3, 4], topology optimization [5], and material sciences [6] projects. This paper reproduce the content of the original publication for BasicTools (Muscat version 1.0) of [7].