You don't need boning caps, you can cut the boning with sturdy scissors and file them round to keep from getting sharp edges.
There is no substitute for synthetic whalebone : r/corsetry
This 10mm wide (approximately 3/8 inch) synthetic whale bone is a bit thicker than our other synthetic whale bones at 1.5mm thick., A light weight but
Synthetic Whale Bone 10mm wide
Bonings for corsetry, which one should you choose? - Secret Times
10 Types Of Corset Boning For Historical Corsetry - Sew Historically
Plastic Boning for Sewing, Corset Supplies
File:Baleen whale sizes.JPG - Wikipedia
Found this on a beach in Kent, looks like an animal, any ideas? : r/animalid
Plastic Boning for Sewing, Corset Supplies
Boning in corsets: Everything you need to know – Miss Leather Online
Bonings for corsetry, which one should you choose? - Secret Times