Late response, but yes, even if you don't sell the originals, it is always a good idea to make up a working version to use, while keeping the commercial one in reserve.
Accidents do happen !
I realised this when I damaged one radius on a set of Rockler radius curves when I was distracted. Ever since, my first job has always been to make a working copy to actually use. There was a further advantage to doing this with those, as I made it on a longer piece of MDF that gave me better clamping options.
Back to Cathedral Door templates. I've a set and I do wonder why, as quite frankly I use one of them and very occasionally another. I've never seen them sold singly, yet most of the sizes I never use and I doubt anyone else does, either.
If any of the Croatian lads want a copy of the popular one, let me know and I'll post you one in MDF.
Cheers
Peter