An attempt:
Manipulate[ DensityPlot3D[ z + y + Sec[x - Pi/6], {x, -2 - Pi*f1, 2 Pi}, {y, -2 - Pi*f2, 2 Pi}, {z, -2 - Pi*f3, 2 Pi}], {{f1, 1.5}, 0, 10}, {{f2, 1.5}, 0, 10}, {{f3, 1.5}, 0, 10}, Item[Button["set f1 = 2.5", f1 = 2.5]]]