This shop seems willing to do whatever is needed to replace a part for you. For a part you want copied, that should be right up their alley. For a part that is missing, you would need to contact them and talk it over.
http://www.thebrasslab.com/
Phone: (718) 381-4724
Email Cynthia: brasslab (at) verizon (dot) net
Physical Address:
221 McKibbin St
Ste 18
Brooklyn, NY 11206