I painted this doorknob and lock on phone using Artrage for Android.
I sketched with the pencil tool first and then painted with the oil brush.
I used a single color throughout. I find that I get better results when I use a very limited pallette of colors.
My initial composition showed more of the door and casing but I couldn't get the right result so I cropped it down. That's one of the my great things about painting digitally.