A single Training Kit is necessary to play the Training Encounters, which is an excellent way to learn the rules of CodeWorld the Miniatures Game. Two players would each bring a Starter Faction Set.
Two Training Kits put together allows for the full core game experience, with four buildings, many small frames, NPCs, etc. Two to four players would each bring their own Bands, comprised of Faction Starter Sets and a number of Individual Miniature Packs for their chosen faction.
The design is that any one player needs their Band and a Training Kit, and will be able to play Training Encounters or Full Encounters with any other player that also owns a Band and a Training Kit, allowing the players to comfortably split the cost of the core set.