A polynomial with integer coefficients is of the form
\[3x^3 + a_2 x^2 + a_1 x - 6 = 0.\]Enter all the possible integer roots of this polynomial, separated by commas.
By the Integer Root Theorem, the possible integer roots are all the divisors of 6 (including negative divisors), so they are $\boxed{-6, -3, -2, -1, 1, 2, 3, 6}.$