Tetr and Lev00 are pre and post-processing tools respectively for DFT codes including CP2K, written by Lev Kantorovich of King's College London.
TETR assists with setting up a system geometry, for example, building supercell, merging geometries from different file formats (e.g. adding a molecule to an existing surface), constructing surfaces, and building molecular clusters.
LEV00 can calculate phonons and IR intensities (via Born charges), compute the electronic density of states, and visualise charge and spin densities.
The CP2K-UK project (EPSRC grant EP/K038583/1) has developed a plugin that allows TETR and LEV00 to run coupled to UCSF Chimera, a visualisation application for molecular structures. This plugin allows interactive visualisation of the systems being manipulated as well as atom selection (as input to TETR).