Armored helmet for a troll, How would it work? Options

[Raven the Tricks...]

I would assume you would have some sort of soft layer arming cap under a full face helmet, so the portion going over the horns can be malleable densiplast that hardens when exposed to an electrostatic charge. You would still have the cool goat horn look, but they would be covered in a layer of densiplast. An interlocking back and face plate would provide the hard protection. I imagine the back portion of the helmet would have a cut out for each horn with a half ring or armor extending around the rear base of the horn and the remaining portion of the back coming a few inches forward of the horns. An interlocking face plate would cover the cut outs, and have a small half-ring of armor for the front of the horns base. Chemical sealing would be handled with a gasket around the horns base surfaced with a woven synthetic fiber on the arming cap and a microvilli ring on the hard armor pieces. The same electrostatic charge that hardens the horn coverings would also seal the gaskets around their base (normal residential windows create a near air-tight seal using the same principle.)

That is essentially the solution I went with in my design, albeit with a touch more technical detail. I still haven't gotten back to finishing the damn drawing to scan though.