After a lifetime of not being able to render curves, I have to say its a true joy being able to render curves straight in Arnold. Below is a paint effects brush called ‘gloppy’ that I converted to curves (Modify>Convert Paint Effects to Curves), with a ramp that defines the curve width (lit with an Ai Sky). More examples here.

The animation below was achieved by keyframing the ‘gap size’ attribute of the paint fx stroke from 1 to 0: