Here is a sketch of our minister giving the message. I had to be fast because I also sing throughout the time of worship, and so when he is done speaking I have to go up on stage with the other singers. This is where not being able to erase doesn't really apply because there is no time to do it. A closer look at certain details will show that I sometimes draw transparently, then use rendering techniques to develop form and hide the transparency of shapes and objects (but not always).
Done with a Sharpie pen.