for a nice hugging modern corset made out of strong coutil, maybe even in multiple layers, I'd definitely use spiral boning (with flat boning near the lacing holes, of course).

but for a pair of 1700 stays I've used the relatively expensive fancy German synthetic whalebone, and it doesn't feel that much different from zip ties.

So assuming that one is able to find zip ties with the proper section (the basic ones are way too thin, but the local DIY shops have thicker ones), if I was making something that historically was supposed to use whalebone (which afaik was also softer than steel boning and prone to shape to the body) I'd definitely consider using zip ties.

Not just for stays, also for stuff like a Symington Pretty Housemaid, or a sports corset from the late Victorian era, where being washable helps.

(Actually, I don't remember whether I used plastic whalebone or zip ties in my summer corset made of aida fabric and tape)

Like girlie, idk what you are making but that's not a properly made corset.