Originally Posted by
Pennyhal
Mix some sand with glue and smear on. Or just put some permanent glue on the fabric and sprinkle some sand on. You might want to use a permanent washable glue.
I have no idea whether this would work .... if you decide to do this, test, test and test again.
Make a sample, such as a mug rug size and wash and rewash in hot water/dryer.
Also, check that it would not be toxic.
My first thought was the hook side of velcro for something rough and gritty.
Burlap was mentioned. And there are some other "rough" upholstery fabrics, particularly the backsides of them, but I don't know what they are called. Corduroy would give some roughness, but is soft and velvety, so not really sandlike.
You mentioned using snaps and you might want to consider other "to do" things ... hooks, buttons/buttonholes, zippers, velcro, shoe laces with holes, etc.
As another thought you might want to contact your national blind association for suggestions and other resources.
I am hoping that you are in touch with his family and have full details, rather than working with assumptions as to his abilities and needs.
How nice that you are doing this for him.