Yes, stiff felt sheets! Found in crafting sections alongside its close cousin, floppy felt.
Scribble Stuff Felt Pens make bold statements! The pack comes with a rainbow spectrum of 24 unique vivid colors. The felt pens glide across paper thanks to the protective plastic nib at the base of each of the 0.8 mm tips. So you can color, draw, doodle and display your many, many works of art without worry or hesitation. These pens are great for work, home and school.
Scribble Stuff 24 Count Felt Pens, Medium Point (0.8mm)
Scribble Stuff 24 Count Felt Pens, Medium Point (0.8mm)
I felt something go pop – what does that mean?” - Olton Health and Performance
Here is how to make quiet book pages stiff
POP-UP HOUSE QUIET BOOK PAGE
stiffened felt Pop Goes the Page
Hooray! It's Haiku!
tools Pop Goes the Page
How to Stiffen Craft Felt –