Spray bombed plastic stock...........tape and some imagination man, and if you don't like it a good supply of paper towels and acetone.
Get the pattern you like and then shoot clear over it. Think 4 coats of Painters Choice "matte" on this one. 3 yrs on that camo paint, looks like new.
Tape and stencils will leave edges/ridges, so the more layers/colors the more topography it will have. Best results are to keep it simple. As usual, the better paint jobs are the result of knowing when to stop.
Do a web search, there are some really nice camo jobs done by others using sponges. Does a killer tree bark pattern.