Re: O.T. message regarding 612 negative carrier
You might give this bloke a try:
...now that he's on the internet, I'm sure that it's easy to deal with him...once went up to his shop in person and it was like rendezvousing with a secret agent...but his stock is extensive.
Reason I thought of him was that i searched for Carlwen carriers but they seem ot have gone out of business...they would make you anything for a price (think $$$$$). Otherwise, stalk ebay for a 6Xwhatever used carrier and file it out to 6X12. I've had to do the same thing to a regular 35mm carier for a 24X58 panoramic camera...having a Dremel helps, having connections to a machine shop REALLY helps. The carriers are aluminum so they're easy to carve up.