Step 1: Set up anything you want to copy.

Step 2: Do /give playername structure_block.

Step 3: Place that block in one corner of your object and hit the DATA button until it says SAVE. Then name your object you want to copy.

Step 4: Place another structure block in the other corner of your object and hit the DATA button until it says CORNER. Then put in the name of your object.

Step 5: Go back to the structure block that says SAVE and hit DETECT. You should see white lines going to the structure block that says CORNER.

Step 6: Still stay at the structure block that says SAVE and hit SAVE down at the bottom right corner.

Step 7: Go place another structure block somewhere else and hit DATA until it says LOAD. Then put in your object's name and hit load. It should appear, like it always does.

CONCLUSION: If this does not work for some reason, let me know! I have remembered this just this moment and I thought I could help you all! Make sure you check out my profile to see more neat stuff! P.S. this saves command blocks and their commands too!