Thanks to an anonymous collector(I think I know who that might be--and if I'm right--email or call me, you-who-shall-not-be-named! I need to talk to you), Barrier has posted some wonderful pages of sketches of Pluto, studies for that famous stuck-on-flypaper sequence in "Playful Pluto"--not only a very funny cartoon bit in itself, but exceptional enough that none other than Preston Sturges chose to feature it in the climax of his masterpiece "Sullivan's Travels"(Joel McCrea's Sullivan is a prisoner in a chain gang, taken for a rare "movie night" at a local black church; when he sees the desperate, beaten, dead-end prisoners laughing their guts out at Pluto's antics, he has an epiphany that stands as Sturges' own personal and professional credo).
Here's just one page--go to Barrier's blog to see more:
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image courtesy of michaelbarrier.com
I personally don't believe that these are gag drawings, but agree with John Canemaker's assessment that they look much more like they'd come from the animator himself(Ferguson, the great Pluto expert). That said, they are more finished than one might expect of 'Fergie', so perhaps Barrier's other suggested possibility is true--that it's the work of yet another, third party studying the Ferguson sequence.
In any case, It's just great to be able to see rare material like this. Many thanks to Barrier and his generous contributor.