I'm not sure if this is beneficial to you or not, but I've recently used a mold-making kit, first using a plaster to make a molding of the knife, then letting it dry & harden, and then using a firmer silicone to make a trainer using a pour into the molding I previously made. The products I've used have come from craft stores and most use something like silicone 30 iirc and don't cost much at all. It worked out really well with the exception being the first time I didn't think to shrink wrap the knife or coat it in an anti-stick gel before making the mold. With the knife you are molding, you might want a firmer silicone given its shape.