The image below is from an earlier tweet since removed. Seems the person is/was working on the first season of The Mandalorian, where everyone ceremoniously signed a Mando helmet upon completion.
Here's another post from Instagram that Johnamarie M. spotted!
The Mandalorian Season 1 Recap
The Mandalorian Costumes On Display At D23 Expo 2019
New Promotional Poster For The Mandalorian
D23 Exclusive The Mandalorian Funko Pop! Revealed
Jon Favreau Shares Dave Filoni Sketch While Scoring The Mandalorian
Jon Favreau Confirms He Is Writing Season Two Of The Mandalorian
Sneak Preview The Mandalorian At D23
New Image Reveals Identity Of Assassin Droid In The Mandalorian
Gina Carano Talks About Jon Favreau And The Mandalorian
This Fan Made Mandalorian Poster Makes The Wait Worse
The Star Wars Celebration Mandalorian Rumor Mill Wrap Up
Jon Favreau Posts Another Teaser Image From The Mandalorian
Star Wars Toy Fair Products Up For Pre-Order At Entertainment Earth!
Toy Fair 2019 Star Wars Photo Galleries
Star Wars Retro Action Figure Line Banks On Nostalgia
New Set Photos From The Mandalorian
First Look At Product For Star Wars: Episode IX & The Mandalorian Arrive On Triple Force Friday
Jon Favreau Teases Star Wars Fans With New Image From The Mandalorian
Jon Favreau Confirms Assassin Droid To Be In The Mandalorian
More The Mandalorian Details Revealed
Star Wars: The Mandalorian Cast Announced!
Has The Plot Of Star Wars: The Mandalorian Been Revealed?
Creatures From Star Wars: A New Hope Spotted On Set Of The Mandalorian
New Cast Members Named For The Mandalorian
New Vehicle Images From The Set Of The Mandalorian
Watch The Mandalorian Being Directed By Taika Waititi, Jon Favreau, And Dave Filoni