Woodworkers of MCB: terminology?

[SignOfZeta]

3D printing...you guys crack me up. Why spend 10 minutes cutting up $1 worth of wood when you can spend all day waiting for a robot to make them out of something more expensive?

[Deus Machina]

That was my first thought, and I probably will. But long term, I'd like it to match.
And if I need to thread it, I don't trust the plastic much for that.

[Rainmaker]

That would be something I'd just slap on the printer, if it were me

[Axel]

Presumably you're not addressing the carpenters of McDonald's so I have taken the liberty of correcting the typo in the title 😁

[Deus Machina]

I need spacers for my shelf. I don't want replace it because it has worked and fit perfectly for my purposes, and I'm just trying to find the best adjustment here.
It's an old-school pillar-and-board style. Cylindrical corner posts, drilled and threaded at the top and bottom, with the studs running through boards between the pieces. So it's open on all four sides, and has a usually-generous 14.25" between.
Except a PS5 is 16".
So I need... spacers? Risers? I don't know what to call them, so my search has ended up fruitless.
Basically I just need eight 7/8"-thick discs with a whole through the center. They will get painted or stained to match, as fits material.