Say you have an arrow that is tipped in a white crown, then take a bucket of water, and with some thinned paint make thin swirls on top of the water you can use two colors also say red and black for an exsample now with the paint floating on top of the water in swirls of two colors take your arrow and dip thru the swirls
slowly spinning the arrow thru the piant and same comming back out, once you get the hang of it is really simple, have fun the speed of the spinning on the arrow will give various patterns.