At the time they were being used on some of the Righteous Harbinger Space Marines, but with the old Armorcast War Hound starting to take shape, we found the perfect opportunity top use them.
The original skulls moulded onto the titan aren't the best, frankly, so using the small and medium skulls to replace them proved to be not only easy, but really effective in updating the look of this venerable and large miniature. On something this big, even the smallest details are obvious!
I really like these skulls and would recommend them to anyone looking to add decorative bits to scenery, troops, and especially vehicles - because who the Hell wants to hand paint all those bastards?!