[fantasybroker]

That's a great tip! I bought an air purifier that has a very bright blue light illuminating the entire room at night.

Now if only I can find a way to disable its annoying on/off chimes.

[Groxx]

I've gotta find a way to stop the touch-sensitive controls on mine from responding to cats o_o.

Because of course they're just on the flat top, where cats like to climb and stand.

[jstarfish]

If you have the one I do (GE portable from Lowe's), just put a traffic cone on it. Ugly but works.

I've tried the upside-down rolling chair mats and even DIYed a barbed-wire mesh from chickenwire; nothing deters them. It's a soothing place for them to sleep atop when running.

Condensation forms under textbooks and other flat planks, which will eventually short the controls as water pools on top.

The only other thing that "worked" was having the exhaust from a 1U rack server pointed at it. The heat initially attracted them but when those fans kicked on, cat met ceiling.

[Eisenstein]

Double sided tape. Cats hate it.

[fantasybroker]

A raised plexiglass shelf/cover, perhaps?

[NegativeLatency]

Nothing that can’t be resolved with a soldering iron and a screwdriver

[e40]

NYT Wirecutter top recommend one? Your description fits it to a T.