You mean use a single PSU to power three Amigas? Medusa springs to mind.
Medusa? Where can I find some info about Medusa? Tried Google search but no results :-(
It just came to my head when you said about it powering three Amigas at once...so yes, no PSU called Medusa.
If you have a beefy desktop Amiga (consuming much more power than usual on 5V line) the 4.5A heavy 'A500 PSU' will power it. If you have one of those, it's worth recapping for sure. I always try to use original hardware where possible, but that's a preference of mine.
Fitting a new PSU into an old weak (not the 4.5A) Amiga PSU case is also a good option in my opinion as things at least do look original still and presumably these modern PSU's are more powerful right?
For years I ran my heavily expanded A1200 from a standard 3A Amiga PSU (060/clockport sound card/FastATA with 2.5" HDD). The PSU failed eventually, but it was perhaps due anyway as it had never been recapped and after all was from 1992. I suppose I was stressing it and it was a silly thing to do, but I still have that PSU and I will fix it when I get round to it!