A single stage OPF-to-carbon preform shape forming method includes positioning an oxidized PAN fiber preform with a female forming tool, positioning a vacuum bag over the oxidized PAN fiber preform, and vacuum forming the oxidized PAN fiber preform into a shaped body. The vacuum formed shaped body (while still in the shape forming fixture) may be loaded into a carbonization furnace and carbonized. The vacuum bag may be burned away in the carbonization furnace during carbonization.