I have used Royal & Langnickel 3ins x 8ins aperture cards and bubble fronts for these dinosaur cards, however, I have had them for some many years I am afraid that they may no longer be available except perhaps on e-bay.
I bought the card blanks and bubble fronts because I loved the thought of cards with three dimensional scenes, but I’ll be honest, most of them ended up in the bin because although I tried, I never seemed to do any good with them, the end effect always seemed lumpy and the folds not crisp enough, whatever I did looked tatty! But since I am now on a major stash busting mission, I have had one last go …. and finally, after all this time, I am happy with the results. 
I was determined to put them together as carefully as I could using double sided tape, as I had invested too much time putting the dinosaur “scenes” together to go in the bubbles to waste them. 
The dinosaurs came from a market stall (again, ages and ages ago) and cost just 60p a pack. I have quite a collection of dinosaur stickers (so expect to see them quite frequently now I am desperately trying to downsize), and although “never out of fashion” I haven’t used them as much as I should.
I put together three 2ins square scenes for each card, with two or three dinosaurs in each, depending on their size and then doodled a few trees and a bit of grass, nothing too artistic, just to add a little more interest.
A shaker card absolutely need sprinkles ….. and for these I used tiny polystyrene balls and I am thrilled with finished results …… finally!!!!! Perhaps, they might even start a new theory that the dinosaurs were killed by of a giant snowstorm!
I now have five aperture cards left, but ten bubble fronts ….. it seems pretty obvious that I should make five cards featuring fish …….. but what do I do with the other bubble windows …….. I am not sure how neat I can be with a craft knife …… hmmmmmm!
