"One should smear cow dung on the floor of My temple. By doing so, he will reside with Me as My devotee for as many thousands of years as he takes his strides while smearing the cow dung inside the temple and on the grounds surrounding it. While smearing cow dung in My temple, as many steps one takes, he will enjoy life in heaven for that many thousands of years." [Hari Bhakti Vilāsa - Fourth Vilāsa Text 15-16]
How to make the pictured cow dung floor:
Use pure "fresh" cow dung and add a little powdered lime (not the fruit) and a little water to make a paste. I added the lime to lighten up the color and give strength. Then apply the paste to the altar floor using a plaster spatula in a very thin coat. Not too thin that you see the floor below, just thick enough to cover the floor completely. Then allow it to dry. It is rainy season here and very humid and it took a week to fully dry. So depending on your local weather the drying time may be different. Also while it was drying I would rub the cow dung floor in a circular way with my fingers to even out the color and any lumps or lines from the spatula. In the end you have a nice and natural floor that is really strong and will last along time.