Insulate active or neutral?
If you mean live and neutral AC mains signals then live must be insulated.  Neutral is supposed to be at ground potential and thus not a hazard, BUT there are numerous wiring errors and fault conditions that could make a neutral conductor dangerous.
I cannot imagine a design of a product that would not insulate both.
Relying on neutral being at ground potential is a bad idea even if only a hobby thing.  Don't do it!
Connecting live to ground (not neutral) should trip your residual current detector (fuse like thing in the electricity panel).  So if you were to touch the exposed neutral in any of these fault conditions, the RCD should save you from electrocution, but I wouldn't want to rely on that.