Step 1: What You Need
Paintings or Item Frames
Ladders or someway to get up high
Step 2: Step 2
Make towers with the building blocks. Make them as high as you want your targets to be and make as many as you want targets.
Step 3: Step 3
Put ladders (or whatever your using to get up the towers) every where in the front of the tower except for the top block for a painting/item frame.
Step 4: Step 4
Put a painting or item frame on the front of the top block.
Step 5: Step 5
Shoot the painting or item frame then climb up there and set the painting back.