I am very into pop ups (aka paper engineering). I have been making lots and lots of tiny little prototypes to help me learn the basic techniques and to get a handle on designing pop ups. I have made a few fancier ones, but I really like using small bits of card to make basic two page 'books'. I'll try to take some photos, but don't hold your breath.
Any how, it's freakin' GREAT.
I started with the first book by Carol Barton, which is just the loveliest thing. It includes a heap of basic 'test' cards that you make as you 'read' through the book.
Then I moved on to the Pop-up Book by Paul Jackson, which isn't so great. In fact, it's daunting for complete beginners, and I've only just started getting a handle on it now, after doing a few of my own and working my way through the Barton book. Thing is, they look really simple, but (as the Jackson book points out) it's not too useful just 'thinking' your way through them. You really have to make them to understand how they work. Even then, there are some which I really don't understand - I look at them and think 'how does that work?' Which is part of their appeal.
I'm only doing basic techniques so far - I'm having so much fun I haven't even begun to work on the more complicated combinations. And I'm not really all that interested in the serious paper engineering stuff - no rubber bands or pull tabs for me just yet.
If you're interested, they have some nice books here. I can't imagine a whole book of popups - they're so intricate and time consuming, so labour intensive, meticulous... I like just doing one-off, one-idea visual 'jokes' or 'puns'. Just a card that opens up with a little pop up inside. The smaller the better - they take less time to cut out, they're a good way to test a technique, and you waste fewer materials.
...speaking of materials...
I'd really like a folder. Most of them are bone, but I'm not that picky. I just use the handle of my scissors now, but something specific would be good. I really need it more for scoring, as I just don't have anything useful for that. I'm also planning on upgrading from my $2 cutting mat to a real self-healing mat soon. And perhaps something better than my cheapy scalpel as well. I certainly need proper paper scissors with sharp points. Of all those things, the one I'll probably end up getting is the scissors - sewing has taught me the value of nice scissors. I have good cooking shears, lovely embroidery scissors in a pretty case, arse-kicker sewing scissors, and now it's time to get serious with badass paper scissors.
And of course, card. I just can't get enough of it. I'm still looking for just the right weight. 250gm is too heavy. 80 is too light. I need perhaps 150 or 100. But it's good experimenting with them all, just to see why different weights are good for different jobs.