Hi! Welcome to LC!
Thanks for the interest in my little project!
So the cardboard is just a form- you could use anything, really. Some use a bowl, a glass jar, a cut up juice/milk carton, or even a balloon!
I wrapped the cardboard form in plastic cling wrap from the kitchen. Using Elmer’s school glue I coated the wrap and added fabric “right side” directly onto the glue as that will be the part that is seem once it’s all done. Then it’s more glue painted on all over and more fabric added as you go. I did a plain white middle layer to add bulk and not use cool prints where no one would see it then the outer layer is glued “right side” up as these fabrics are seen from the outside of the bowl/project.
Glue the heck out of it (it is a messy-ish project. Think papier-mâché - your hands will be glue-tastic) and let it dry for at least an overnight.
Once it feels dry you go ahead and free the shape form from under the cling wrap and carefully remove the wrap from the fabric. That inner fabric will still be a bit wet so go slowly. You may need to touch up/add some glue at this stage if things pulled up a bit. Then you air dry it again for a while. When it’s done it is really stiff and holds its shape well.