Alright, so as per the rules of the Invisible College invention rules: Start with TN five and a drama die, add 1 for every year after 1668 it was created in actual history, add +10 and a drama die for each leap of logic (which seems about right for "use of peculiar dice to determine outcomes for a fictional character for the purposes of gaming"). That brings it to a conception check of TN 346 and two drama dice. For the design check, size doesn't apply really, so base 5 plus 5 for "uncomplicated" complexity, plus 15 for the leap of logic, so tn 25 there. For Invention, base 5, plus 10 for Delicate (more delicate than an iron bar, less delicate than a clock spring), +10 for Medium Size (the whole suite of books isn't handheld, but is smaller than man-sized), +20 for the leap of logic, for a total of 45.

tl;dr: tn 346 and two drama dice to conceptualize, 25 to blueprint, and 45 to physically produce.