I grabbed two coordinating towels which were in good shape except for the worn and fraying outside edges. I measured the floorspace in the guys bathroom and cut the towels to fit it.
I thought two layers of towel would be more comfortable to stand on, as well as making the reverse side more interesting. I finished the edges using some 'manly themed' quilting cotton as binding. Now there's a practical, easy to care for mat for them to use and I can cross this project off my Spring to Finish list.