This is a really cool command block creation for anyone who likes to paint. It works much similar to MS Paint in that sense that you will be able to select among a wide range of colors and then use a paint brush to paint. However, it can sometimes be a little bit tricky seeing as you need to throw the paint at the canvas (similarly to throwing snowballs) and sometimes you might miss.
Creator: Jhomes, Twitter Account
Press the button on the side of the command block creation to spawn the chest which contains the three different paint tools.
Then make sure to select a color for the paint brush.
Use the Spawn Canvas item by tapping on the ground anywhere that you want to spawn it. Then use the paint brush similarly to throwing a snowball to splash some paint on the canvas. You can return to the command block creation at any time to select a new color. Just make sure not to forgot to disable the previous color.