A year or so I asked this of the forum..
And although I haven't spent the time to fix those antlers.... I did just recently use everyones information on there to thix these moose antlers.
Using Bondo Glass, Bonda Fiberglass MAT (notbondo cloth because the mat is stronger according to bondo and the same price, but either would probably work just about the same?)
Drill holes to give the bondo glass something to bite into...
If you haven't worked with the stuff before, only try to do small patches as you will not have the time to do the whole or even half the project at once since the stuff sets up so fast.
I cut a pop can in half, cleaned it out, glopped about a 1/2 or so of the bondo glass in the bottom of the container, they put a thin straight line of hardener across the top, mixed it up, threw it on, worked it in and worked some 3 inch wide strips of fiberglass MAT into the bondo glass... (use gloves, and mask off the antlers to not get any of the junk on them) did a couple-few layers over the break, and then finished off with a layer of bondo glass to coat the top of the last fiberglass MAT... I Started with a bunch of Bondo Glass in the crack so then I clamped it together it was forced into the holes and forced out the crack to be used to start covering the crack for the first layer.... it seems very strong...
As you can see some of the hardened Bondo Glass is Redish Brown from too much hardener mixed in, some is blueish from just enough and so forth... but I'm happy the outcome... They aren't going to fall apart as far as I can tell.