Bill Houghton, Sebastopol, CA
Garrett Hack, in his plane book, shows two versions of a patternmaker's plane with an iron body and interchangeable wood soles with matching irons. I've been watching, so far without results, for such a thing to appear in my neighborhood.

In the meantime, will regular wood bodied hollowing planes work for your application? They're not hard to find, and you can get different shapes in quite a range of curves.