I've begun an elaborate Valentine's Day present for my sweets: a book with 5 things I admire about him and each thing will have a different paper engineered mechanism that makes it interactive. This first item has proven to be a real brain-bender for me because while I can usually follow my pop-up guru Duncan Birmingham's videos and make subtle modifications for my need, this one demands more freestyle engineering than any past projects.
Need: An arm to rotate at the shoulder when the page is opened without having to manually operate the mechanism (other than opening the page).
Final mechanism used: cross-page pull strip with hub and rotating pivot.
1st attempt: using a moving arm on an elevated plane.
Why it won't work: I can't have the image on an elevated plane. I need it to be level with the background I'm using. This is a pretty remarkable technique, though.
2nd attempt: using a pull tab with hub and rotating pivot.
Why it won't work: This is the basic idea of what I ended up using, but the trick is getting it to function on its own (insofar as the opening page controlling the movement) without having to be pulled manually.
3rd attempt: using a pull tab with hub and rotating pivot starting on the opposite page.
Why it works: The tension from the strip being glued down on the left page pulls the strip taut, which slides the hub and thus, rotates the pivot point.
Cons: The strip has to be exposed at the crease to enable the strip to be loosened before being tightened, so it loses some of the magic in the motion. I'm also struggling with the strip creasing at the wrong spots when the page closes, so it doesn't work smoothly. I'm going to experiment with some less fibrous papers.
Stay tuned for the next page!