Facsimile Ernest Nisters are readily available and inexpensive.

Rubin stressed that because their charm depends to a large degree on how well they function, condition plays an even more important role in determining their value than in other parts of the book world. Also, because so many of them were made for children, and children seldom kept them in pristine condition, even pop ups with larger printings are often hard to find in truly collectable condition.
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Rubin notes that pop-ups and movables go back to the 13^th century but popular interest really gains momentum in the late 19^th century with the work of Ernest Nister and his contemporaries such as Lothar Meggendorfer. 

Enthusiasm waned with the passage of time and then picked up again in the 1970s. In her opinion, “It reaches its apogee in the mid-1990s." She also noted that pop-up and movable (non-book) ephemera of all periods is becoming more valuable, sought after and plays an ever increasing role in her own collecting.

Rubin said that while interest in the field continues to grow and prices paid for rare or unique items are on the rise, the actual making of pop-ups, like other aspects of publishing is diminishing.

Typically, she observed, “collectors go in for the WOW effect. But presently, the number of paper engineers working in the field is shrinking and publishers are ever more reluctant to commit funds to large and expensive formats that are entirely dependent on hand assembly. Where before you might have seen a book that measured 10x12” with nine unique spreads, now it’s more likely to be 7x9” with far fewer and less complex mechanisms.”

Asked to name her current favorite she mentioned Knick Knack Paddywhack, a children’s book done as collaboration between illustrator Paul Zelinsky and paper engineer Andy Baron. She is quoted in the promotional material for this title as saying “This book has more actions linked to a single pull tab than any other mechanical book since Meggendorfer.”