Wikipedia says this about a Menger Sponge: "In mathematics, the Menger sponge is a fractal curve... The Menger sponge simultaneously exhibits an infinite surface area and encloses zero volume."
I purchased blank Shoelace Charms on Etsy and once I received them, got started using Photoshop to create the correct size logo. Once I created the logo, I printed it on glossy photo paper. Then I stuck the adhesive clear covers over the logo and cut out around the cover. I attached the covered logo to the charm by using Krazy "Craft" glue.