Looks like there have been some casualties to my vague and convoluted way of thinking about, and expressing what, I was wishing to accomplish.... I apologize for that...obviously I am the one that does not understand and lacks the experience to formulate the question.
I had initially made the assumption that the segments of film had to be in the same holder in order for the registration of the edges to link up precisely... as they were to be contact printed then blended. This also seemed to me to be the way to keep the visual perspective when using movements. It also seemed to me the way to keep all the elements organized. I also had other idiosyncratic aesthetic reasons...... if you refer back to my original question it is apparent that I was unaware of the concept of darkslide masking as a means of gaining different exposures.
For me there are now some wonderful new possibilities and methods that have arisen from this thread that I can explore with masking as well as simpler approaches to the colour and B&W mix. Thank you all for your kind input and creative solutions.
Send me some dimensions by PM. Need them to be pretty exact, within 1/32nd if possible. Plus I will need a thickness, probably best achieved with a caliper or a micrometer. Then you have to determine how you want them cut out, and give me those measurements. I am not sure of the price, but I will charge you my cost on the metal, about $12-15 to cut each one and then shipping cost. I use to be able to get plastic very similar to modern darkslide material. I may be able to get that (better alternative) depending on the thickness required. They won't have a handle, but can cut a hole to use to pull with and mark one side for exposure made.
Great Jim, I will measure Sandy's holders and send them to you, thanks!
I'll tell you the biggest problem I've found with ditychs and triptychs. It's uneven exposure/development at the edges of the negs (now that's probably due to development in open trays, but something to beware of nonetheless). Check here:
Annie, I've gotten to the party way late as usual but for future use here's how I would approach it. The old 711 holders are loosy goosy enough I think. I'd slide a piece of 5X7 film to the end. Maybe B/W. Then I'd slide a piece of 5X7 Velvia in and overlap the first sheet by an inch+. Now there's an equal 1/3 of the first piece. Then I'd cut my final piece (B&W paper??) to the dimension of the first and second piece and slide it in to overlap the middle piece. 3 different substrates will then be in position with equal 1/3rds of the full 711 when a single darkslide is pulled to make an un-interupted triptych (sic?) on all three pieces of material. The difficulty might be getting 3 pieces that will all "see" the same exposure correctly. PanX and Velvia are about the same speed but b/w paper is VERY slow. Confused??