During the course of diagnosing and fixing the latest oven igniter failure, an unrelated series of events produced a flood under the kitchen sink and across the floor. After cleaning up the mess and determining the floor under the cabinet was merely damp, rather than wet, I drilled a hole suitable for another PC cooling fan from the Box o’ MostlyFans, installed the fan to pull air upward, and let it run for a couple of days while watching the humidity drop.
Fortunately, I had a hole saw exactly the right size for an 80 mm case fan:
I will lay big money on a bet saying your kitchen cabinets don’t have Real Wood like that, nor are the interiors painted bold Chinese Red. This place really is a time capsule from 1955.
While the drying happened, I made a hole cover from 1.5 mm black acrylic and, there being no style points involved, rounded up a quartet of black-oxide self-drilling sheet metal screws to hold it in place.
Although it’s not obvious, there’s a layer of transparent plastic “shelf paper” in there. It covers the fan hole under the cover, so any future spills will have approximately the same difficulty reaching the floor as this one did.
The LightBurn layout produces both the fan cover and a template to mark the four screw holes around the fan opening:
The blue tool layer lines serve as a guide for the rest of the cover layout; the matching orange square on the right marks the fan outline on the drill template as a quick size check.
No need for an SVG version, because now that you have the general idea, it’s easy to recreate it for your own fan.
The Smell of Molten Projects in the Morning 
my house is 1950, and the cabinets were real wood, before we updated. The interiors of some were red, too. I do kind of miss the cabinet going all the way to the ceiling.
Another time capsule lost to history! [grin]
Which reminds me of something you don’t see anymore: A slot in the back of the bathroom mirror over the sink where you were supposed to dispose of dull razor blades behind the sheet rock. I can’t understand how the manufacturer thought this would be worth the extra cost to punch the hole and put a label on it.
I was there when my father tore the sheetrock off the bathroom wall while rebuilding the adjoining bedroom and released a cascade of razor blades …