Using a piece of flint you can modify armor stands in a more meaningful way. Simply right click while holding the flint to open the editor.
Press the "switch hands" key (Default is the F key). This will select the armor stand you wish to edit.
While looking away from the armor stand, right click with the piece of flint. this will open the editor menu
Inside this menu are a lot of options. You can make adjustments like making the armor stand invisible, displaying the arms or even making it tiny!
For now start by will clicking the "Show Arms" button, it looks like a stick on the right hand side of the menu. This will set the mode to "Toggle Show Arms" Exit the menu and right click on the armor stand.
Now that our armorstand has arms, lets make wear a block on its head!
Go back into the editor and select the "Equipment" mode
Now if we right click on the armor stand we open its inventory
Try adding a block to the armorstand's head!
lastly we will attempt to make our armor stand wave! open the menu again and select "Left Arm Position", then select "Z Axis"
Right or left click on the armor stand to move its arm
This tool can be used to create any number of cool decorations. Test out all of the features in the menu and get creative!