each one of these you move the a value around

sin waves made out of sin waves

y = sin(ax) + a sin(x)

splash (x-cos(x-a)^2)^2 + (y-sin(y+a)^2)^2 = a

optical illusion? cos(x) <= xa sin(y)

dir strange portal tan(x^2 + y^2) = a

circle made out of sine wave circles x^2 + y^2 = b sin(ax)

affine plane cos(ax-y) = sin(x^2 + by^2)