Might be able to, but it would add to the cost. Likely more than it's worth to have them hollow. The originals were several stamped pieces and assembled back when labor was cheap.
Paul
I'm sure you saw some samples displayed on their website. That is the finish the castings make. It's amazing at how small and fine the details are that lost wax castings can copy. The basic process is thousands of years old, but modern methods make the process even better. That is why the pattern part you send him has to be as smooth as what you want the castings to be.