I wouldn't do 3X with a 6x9 camera hand-held. It is too awkward using a technical view camera in that manner. However, in a studio setting there would be little problems. Or I could switch to my Nikon Multiphot photomacrographic camera and use the Macro-Nikkors in leaf shutter mount.
For 3X with the DSLRs, I'm using a rig with an Olympus 38 mm f/2.8 macro lens. Once in a while even shorter lenses, such as a Macro-Nikkor 19 mm f/2.8 or Canon 20 mm f/3.5. I probably should track down an Olympus 20 mm f/2. I use the Olympus simply because it has a sensible size to allow me to operate it with gloves on. That is less easy with the other alternatives such as the Macro-Nikkors (apart from the 65/4.5 Macro-Nikkor, but that one is better used with the Multiphot).
Do note the ring arrangement and the protruding stub in front. This acts as a combined stray light baffle and a holder for the SB-21 ring flash. The perfect setup for easy hand-held photomacrography. Still, there will be a lot of captures outside the optimal focus, but getting the keepers is no longer verey taxing as only patience is required.