Most of Douglas MacKrell's videos are filmed in front of his bookshelf, which content changes over the course of his meetings.

  • a Back to the Future-Delorean by Sun Star
  • undefined Merchandise to Evil Dead the Musical
  • "Book of Greek Myths" by D'Aulaire
  • a book about art, most likely "A World History about Art" by Hugh Honour and ‎John Fleming
  • "Truffaut, Hitchcock" by Francois Truffaut and Alfred Hitchcock
  • "Great Americans"
  • the red book about "America" could be "Mysterious America" by Loren Coleman
  • "An Alchemist's Primer: Fundamentals of Esoteric Transformation" by Manly P. Hall
  • a picture with Scrooge McDuck in the design of his video game
    • also a tuning fork in front of it as an illusion to the DuckTales-episode "Treasure Of The Golden Suns, Part 4"
  • a figurine of Captain Crunch, most likely this coin bank
  • ROOTHM-tapestry
  • a magnifying glass
  • "The I Ching or Book of Changes" by Wilhelm and Baynes
  • "Deadly Equines" by CuChullaine O'Reilly
  • "You can communicate with the unseen world" by Harold Sherman
  • "Great Tales of Horror" by H.P. Lovecraft
  • a guitar leaning at the buttom right

After his puzzle challenge MacKrell added a few more books to his shelf.

  • "777 and other qabalistic writings of Aleister Crowley"
  • "The Areas of my Expertise" by John Hodgman
  • "The Zombie Survival Guide" by Max Brooks

The last one was replaced in Dipper's Real Name Theory Debunked with...

  • "The Quantum Leap Book" by Louis Chunovic

...only to be replaced again in the next meeting The Mystery of Pacifica Northwest with the previous "Deadly Equines". MacKrell also appended...

  • "Seth Speaks" by Jane Roberts

...which was also gone the next meeting The Mystery of Gideon Gleeful. Added in "The Six Fingered Hand" was a yellow undefined book. Another unidentified book with a big 10 on its cover was appended in " Candy Monster".

" Stan's Tattoo" added two more things to the shelf.

  • "Astrology: A history" by Peter Whitfield
  • the Great Owl Rockytop
  • a little yellow rubberduck

The Update Video 6/7/14 showed the lower shelf with a toy horse and rearranged a few books. 

In The Mailbox MacKrell appended a photo he got mailed from a fan and in his Patreon Announcement a pressed flower.

Lefty had his "Book of Greek Myths" by D'Aulaire presented more prominent, MacKrell also added a book about UFOs.

  • "Flying Saucers - Serious Business" by Frank Edwards

In The Tooth he appended two new books.

  • "The Thrilling Adventure Hour"
  • Book of Thoth

In Scary-oke two more books were added.

  • "101 Spy Gadgets for the Evil Genius" by Brad Graham and Kathy McGowan
  • "Reason to Believe: A Practical Guide to Psychic Phenomena" by Michael Clark

In Decoder Ring Depletion he appended...

  • "Dinosaurs - Giants of the Earth" by Dougal Dixon

...and in The Secrets of Scary-oke the long-titled book...

  • "Chakra Meditation: Discover Energy, Creativity, Focus, Love, Communication, Wisdom, and Spirit" by Swami Saradananda
  • a painted My little Pony-figurine MacKrell got for his Creative Contest

Into The Bunker showed us this Collection of short storys.

  • "Alfred Hitchcock's Supernatural Tales of Terror and Suspense"

In The Secrets of Into The Bunker he added another two books.

  • "The Unexplained: An Illustrated Guide to the World's Natural and Paranormal Mysteries"
  • "The Field Guide to Lake Monsters, Sea Serpents, and Other Mystery Denizens of the Deep" by Loren Coleman

Two new books were appended for The Golf War...

  • "Amazing America" by Jane and Michael Stern 
  • "Signs, Symbols & Omens: An Illustrated Guide to Magical & Spiritual Symbolism" by Raymond Buckland

...and two other for Puma Shirt Panther Shirt Phantom Panther

  • "The History of Freemasonry" by Albert Mackey
  • "Tales of the Cryptids: Mysterious Creatures That May or May Not Exist" by Kelly Milner Halls

In The Blindeye Society MacKrell added

  • "New Roadside America: The Modern Traveler's Guide to the Wild and Wonderful World of America's Tourist"

It's not his shelf, but in Creative Contest Winners we get to see MacKrells Mac and also...

  • a cup from Confusion Hill
  • a model of Tom Servo
  • three TMNT-figurines
  • the winning owl-figurine

In the meeting MONSTER OF THE WEEK versus MYTHOLOGY EPISODES two more books were added.

  • "The Field Guide To UFOs: A Classification Of Various Unidentified Aerial Phenomena Based On Eyewitness Accounts" by Dennis W. Stacy
  • "Dipper's and Mabel's Guide to Mystery and Nonstop Fun" by Rob Renzetti and Shane Houghton