Bah I am not as imaginative as you guys but probably the thing that took so much effort to make was a metal engraved poem on a custom frame
I used to work at an engraving place so I had the materials to make the thing, but it was a bitch to first write the entire poem out, design the format, and finally engrave the bitch.
The first time it messed up and punched a whole through the metal, the second time it had a spelling mistake

. Finally the third pass I got it right.
But seeing her face after seeing it made it all worth it!