Nice office gadget. Making difficulty level 3/10
Hexagon holes in the frame are not incidental.They are slightly bigger than a pencil that fits there. It works as a brake but does not completely stop pencils from rotating. That allows to create a tension of scrolling material and keeps it straight. It is also fun to use long forgotten, old fashioned wooden pencils ;)

GATE 3novatica

Doesn't Matter

No

0.4 works fine

20% is enough

Once you print 4 rollers and the frame you will need 2 hexagonal pencils to spare. Cut pencils to the proper length so the rollers are firmly fixed and almost touching the frame. I needed to file them just a bit on each end to fit in rollers hole.
Then a piece of calendar or other staff you would like to scroll must be attached to the pencils. I simply made it with a stripe of adhesive tape.
This frame was designed with a window of 70x95 mm - a sample calendar is attached so print it without scaling on A3 paper or bigger.