In search of multi-cam mounting tips

Longtime photographer, artist and more recently a videomaker here, now experimenting with collage-like time based art – specifically via video- a la David Hockney. I’d like to stack three identical cameras (Lumix GH6) with compact lenses. High precision is not required, but stability is. I have cages for the cameras, but before I buy cheese plates, NATO rails or clamps, etc. I thought those of you with a lot of experience in mounting cameras in unusual configurations might have suggestions.
I’m imagining a relatively tight vertical stack atop a tripod, though the cameras are small enough that a technically handholdable setup could be worth an experiment too. I don’t have to accommodate any external focus mechanisms, matte boxes, external power sources or monitors. One version could simply have the cameras fixed on axis; another version could accommodate left/right pointing adjustments, or even slight tilts.
Any pointers or reference images?

(I’ve also posted to r/cinematography)

Thank you.