If you want to go the route of hydro print the best bet is to have it done professionally since it usually isn't all that expensive. I would suggest
Hydro Print Canada. Frank has done work on pretty much everything you can think of including airsoft.
Another option is doing the frame in a more resilient coating than just spray paint. You could use Duracoat or Armacoat. I know Armacoat offers full kits for around $60 and they have a good selection of colors. There is another alternative that is simple, cheap and durable. It is Duplicolor Engine Enamel Low Gloss Black DE1634. It is both bake on and air cure and it is pretty much as durable as Duracoat or Armacoat.
You can always keep it cheap and simple and just use some krylon fusion camo paint and a flat clear to finish it off.
I personally think it would be pretty cool to see it done in some kind of hydro print like multicam.