Single light between 3 way switches (power via switch)

Power enters the circuit at switch box (SB1) and the hot connects to the common terminal of the 3-way switch (SW1) and the neutral is spliced through to the neutral terminal of the light. The travelers from SW1 (via cable C1) are spliced at the fixture and carry on to the second 3-way switch (SW2) via cable C2. The common terminal of SW2 supplies power to the hot terminal of the light.

Single light between 3 way switches with the power feed via the switch