Pavia team has experience in Geant4 from CMS and Muon Collider activities, with simulations of RPC and MPGDs (GEMs and PicosecMM). Involved since more than one year in R&D of PicosecMM for Muon Collider applications, now would like to complete the study with also the simulation part, especially for the search of new eco-friendly gas mixtures.