OK cool , look for a product made by upol called raptor liner it has a nice tex but a bit rough an possibly too expensive as you can only get it in a kit thats a gallon an qt of hardener. what you may be looking for an may also better suit your needs is one called gravtex made by the same company it goes on some what smoother an is nearly as durable once its cured , an available in quarts only it also comes in 2 colors gray an black an is also paintable, its really good stuff we use it at work its a factory stone guard on porsche, audi bmw an mercedes . in our area most of the automotive paint supply stores carry it .
heres a couple links
hope this helps ya .