Nice idea but any small crap can cause problems later for any jack opening up. Worse are jacks w/ "closed" cases to collect and keep crap inside.
I've clean/fix many jacks on top of PC and more for this reason.
You may never put things in the ashtray but junk can still get in them w/ a door won't seal them.
Similar problem w/ cig lighters open up and crap falls in and often shorts out. Fiero isn't only car w/ lighters in iffy places, worse w/ people using "power plugs" taken in/out and don't plug the hole when out.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave