Hi!
I'm not very good with explanation. But I'll try.
I used geofoam, stationery knife, sandpaper, PVA glue and acrylic paint for horns.
I cut both horns form from geofoam with stationery knife. Then I used sandpaper for smooth surface. And after this I coated horns with PVA glue about two or three times. Horns dried and I colored their with acrylic paint.