Complex sentence: Starting with these three members, Tom began planning a project that would incorporate a huge band sound with "a large palette of instrumental colors to work with" and thus started laying the ground work to what would become Thank You Scientist.
Split into simpler sentences: Starting with these three members, Tom began planning a project that would incorporate a huge band sound with "a large palette of instrumental colors to work with". Thus laying the ground work to what would become Thank You Scientist.