I tried batch painting a light blue metalic ford two years ago.
Good news was that soda blasting worked on bonnet/bumpper on small chips raised by stones and other road wear.
I tried one of those canister sand blasters, it works on sand, but not on soda. I bought this and it needs a little adjustment, but works great on cleaning/abration and I don't need to worry too much if getting abbrassive grit on palves where it does not belong.
http://nordblasthome.com/en/However, although painting workked really well on solid colors (bright shiny red on my wife's car) it did not work that well on my three paint system metallic color. Small spots of 3-5 mm were fine, but bigger ones produced python coloring and I took it into professional pait shop....they told that they could have done the same work, same price

But I learned something.
I have small grit pot type too. Works, but needs a big compressor, very dry sand and good wattertrap.
Pekka