Several prototypes were made prior to the final product.
The 1st paper model was made to design the shape of the upper, and possibility of pattern.
The 2nd paper model was made to finalize the upper and the pattern
The felt model was made to realize the slipper in the same material, and to test the comfortability.
The seam in the middle bulges up the shape and turn the flat pattern into a 3D form.