Sharpie help?

The sharpie should work just fine...i suggest u use a regular pencil and draw out the design first though, then go over it with the sharpie...also u might not wanna do it all at once...do 1 part first, let the ink dry, then do the other part to avoid smearing the part  already done while doing the other pt ...the only problem with all these things is they can smudge after a while, so be weary of water whether u use the sharpie or the paint...especially the paint.

My aunt just told me after u put on the design using the sharpie or paint...let it dry (i mean really dry) then u can paint over it with clear nail polish and that should both make it so water wont damage the design and make it last longer "not to mention make it look shiny,"...i have never done this however so i dont know how well it works, but it does seem to make sense...maybe one of our LOVELY LADIES on this site will help to confirm the nail polish.

Thats what my aunt said...i really cant say for sure if it does, thats why i would like to see some of the ladies on this site give a respones, cuz they would know.

DO NOT spray paint your phone case. I discovered it just cracks it and makes it look very cheap.

if possible, i'd suggest to check the medium(s) you're planning on using to make sure it's safe for rubber surfaces? rubber's not a very durable material to begin with (compared to plastic). i'm just weary that slapping on chemicals will shorten the rubber's lifespan. the water soluble (washable) paint doesnt sound like it would hurt the case at all, but i doubt the color will stay bright for an extended period of time.
there are acrylic sprays out there that artists use to "fix" drawings so to protect against smearing. but i'm not sure how effective those are on rubber surfaces. :/ but you know, i say, just go for it and then you can tell us the results!