The fabric used as the sides of the box, and to diffuse light sources, contains pockets which are able to house the dowel rods. These rods are not set in place and can be removed, allow the fabric to collapse onto itself and folded away in a case, which can then be carried around with you. When you need to set up the light box, all you’d have to do is insert the dowel rods into the pockets of the fabric, which will then pull the fabric taut and hold it in place.
It’s a rather ingenious solution, although we’re not sure exactly how many photographers would need to bring a light box with them wherever they go. However if a light box is something you need for your photography, and its portability is just a bonus feature, Hharry has mentioned that it will cost you $40-$80 to build the entire thing for yourself. Head on down to his Instructables page for the full list of materials and instructions.