I don't know if I saw that lantern slide, Ron, but maybe.
I have a Beseler Slide King, which can take lantern slides, so I searched at one time for lantern slide mounts, and I couldn't find any. My thought was that I'd mask them down for 6x6 and 6x7 slides. Of course there are mounts for those formats, but their outside dimensions don't necessarily work in the Slide King's slide carriers, so I may end up just modifying one of the slide carriers to take a mount that Gepe makes or maybe having mounts cut from mat board with the inside dimensions of 6x7 and 6x6 slides and the outside dimensions of a lantern slide. I cut a few such mounts by hand, and the projected slides look fantastic.