A cubic core is a structure made by folding a single plate with square holes at equal intervals punched on it. Like a honeycomb core, it is lightweight, thick, and has an excellent structure with a certain level of strength. We first propose a method of creating a cubic core by assembling (or weaving) paper strips into a grid pattern instead of punching holes. This method involves preparing paper strips of a certain width, arranging them at equal intervals, gluing them, and folding them. The advantage of this method is that there is less waste compared to normal methods, and parts are easier to manufacture. One of the characteristics of a cubic core is that its top and bottom surfaces form an uneven checkerboard pattern. It can be better to have a uniform height on all surfaces. If the checkerboard patterns of two cubic cores can be stacked one on top of the other, by filling in the recesses with each other, it is possible to create a cubic core with the same height on all sides. We introduce it as a double cubic core. A double cubic core cannot be made by combining two plates with holes. We propose some methods to create the double cubic core. Depending on the method, it is possible to create arbitrary dot patterns or restricted dot patterns. We show a design of a font using such a constrained dot pattern as an application of the double cubic core.