There is a reason I prefer compact keyboards, no room for bigger ones.
I have had one stack in the corner for years, for the security Pi's basestation made from a hardware store DIY 300x600mm wide shelf $5.
Two 90 degree shelf brackets, one front and back keep it upright.
The shelf is vertical and at 45 degrees to the corner walls with power board and power supplies hiding on the back
Pi's in any old cases and 100Mb/s switch on front screwed to the shelf.
Very ugly, but not touched for years apart from the occasional SD card fix or Hard drive swap.
Vertical mounting reduces the places dust collects
Most of my 24/7 older Pi's are distributed around the property.
Lunch boxes/storage containers from the supermarket are good low cost weather proof cases.
Some have very clear plastic, good for the cameras.
But now with so many Pi variations and OS's, using just one Pi as a desktop is not enough.
Solutions for a stack of fan cooled Pi's are of interest.
One Pi4 is a low end Desktop replacement, but when I have a bramble of Pi's I am into new territory.
Using Pi's for development requires a stack of Pi's as no one OS is winning yet.
It's like a horse race, Gentoo64 leading Buster by a nose, followed two lengths back by Arch, then Ubuntu and these rest in a group with the favourite PiCore coming in last.
Back to cleaning the desk to make room for the new 1GB/s Switch stack.
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges