This is a logo/emblem design I had made for Site-Spec last year, with the intention of using it for other stuff too. I refer to it as “Hammerspace”, and whilst I understand if it’s not exactly what you’re all looking for, it’s a good jumping off point. I also have a Illustrator file for it, so it can be resized or tweaked to specification.

For those who don’t know, “hammerspace” is the name that’s used in cartoons and similar media for any pocket dimension from which something is retrieved as if from nowhere, usually hammers, hence the name. When Felix the Cat pulls improbably enormous objects out of his carpet bag, or when Ramona Flowers pulls an oversized mallet from her teeny-tiny purse, they are said to be retrieved from hammerspace. The TARDIS from Doctor Who is similar in terms of its relationship to 3D space, i.e. it is “bigger on the inside” to the point where it is potentially infinite.