-wear your panthose
-start free-drawing on the pantyhose's surface
-wait until the paint dry, take it off
-slip newspaper/some cartons inside each pantyhose's leg
-repaint to achieve the vivid black color for your cross (or anything you'd like to draw)
-wait until it dry again
-apply top coat on your crosses!
-ta-dah, you're done!
so this is how it looks like when i wear it :
I also made DIY skeleton tights. It is basically the same method as to make the cross-tights one, except that I used google to find skeleton legs images as my template / inspiration.
So choose whatever motive for the tattoo tights. Have fun!