Camouflage is a very popular design and unless you do soft edges like the WWII designs, it can be quite time consuming to paint with all the masking you need to do.
Here I tried a pretty simple method. It is done with positive masking and spray in all the negative spaces. Please note that all colour used are opaques.
First you take your surface you want to paint and cover it in the first colour in your design. In this case it is black so I skipped the painting part and used black card stock.
With a swivel knife I just cut random shapes out of Avery Sign Mask material and stuck it on the board. You can cut these shapes with a vinyl cutter as well. That will give your smoother edges.
This basically finishes your first colour and you can put your next colour down. In this case it is a sand colour.
With the mask for the black still in tack, I cut some more shapes and randomly place them on the board. This now saves all your brown shapes.
With a light green I did the next colour.
Some more masking to protect the light green bits and ready for the final colour…
…which is dark green. By this time you can only spray over the spots that are not covered by masks. Can save some time and paint.
Depending on the design, four colours should be enough.
This is what it looks like with all masking removed.