Using this video tutorial for spray painting stripes onto pants, I have turned a pair of brown cargo pants into the pants that Blaze will wear with his Halloween costume.
The painter's tape came from our local dollar store. It's more narrow than the tape used in the video, but since the pants are also smaller, I figured that worked out fine. I used a ruler as the divider between the lines of tape as I laid them down, so that the stripes would be evenly spaced, as much as possible.
I did not use regular spray paint, but I wish I had. I used spray-on fabric paint, in opaque black. It took three bottles to completely cover the pants, which made this much more expensive than the regular can of spray paint. If I do this again, I will follow the instructions and buy spray paint. Still, the pants turned out good and Blaze is happy with them.