I am part of an Engineering Design and Development class and I'm thinking of designing a device that would allow vertical adjustment of pictures that are already hanging on the wall. Could you please tell me what issues you have when you're hanging a painting or picture? Also, how much would you pay for something that allows you to adjust the vertical height of the picture with the picture frame already hanging? I’ve heard this is an issue for many people and i would like to get your input. Also, are you aware of anything that resembles a vertical adjustment on hanging pictures? Any help you could give me would be appreciated. Thank you.