Im looking for a 116/616 Omega D Negative Carrier 2 1/2 x 4 1/4 inch opening
Thanks
Until you find one of your own, make one out of flat black matboard, use a Sharpie to darken the white edges inside the opening for the image, and hinge both sides together with gaffers tape or black cloth duct tape.
Use new Straight, one sided razor blade(s) to cut open the opening and leave a handle projecting out from the enlarger mouth. cut off a large enough piece of the tip of the top handle so separating the device is easily done, without prying.
I freelanced and did B&W darkroom work for years and can no begin to tell you how many thousands of prints I made on such negative carriers.
By the way, I have both an Omega 'D' and 'E' , on my bench right now, (and a Leitz Valloy II) and even though I have a great spread of Omega carriers, I sometimes still use such a carrier because of the delicate nature of some too thin films.
Good Luck.