-TA Crosspost-
While the solutions already submitted are fantastic if you want to get it legitimately, there is a much easier method for those of us without morals.
If starting from scratch or to preserve your current world:
*** Spoiler - click to reveal **** Start a new game.
* Create your Sim.
* Choose a location to move into. Purchase the land.
* Save and go to Manage Worlds.
* Choose a neighborhood.
If you don't give a fig:
*** Spoiler - click to reveal **** Load game.
* You'll automatically be placed in the Manage Worlds screen. Decide now if you want to use your current neighborhood, or another (click on the Earth icon on the top left if you choose the latter)
* Go to a vacant lot, choose "Create New Household to Move In"
* Create the new Sim.
* Go back to the lot on your most recently created Sim. Click on lot, and go left two icons to "Build".
* Go to Objects by Function. Note that where your monetary details would be normally is an infinity symbol.
* Go to Activities and Skills, then Creative. Find the object "The Virtuoso Violin" for 15,000 simoleons.
* Put down about 70 of the suckers. On the account I verified this with, I wrote out ROSEBUD using 5x7 letters just to be cute.
* Save. Return to Manage Worlds.
* Go to your violin-laden plot. Press play. Let it load. Receive Achievement.
Do not attempt to do this with a Sim you've already played with, as building edits will cost simoleons.
Instead of creating a new Sim to work with, you can also use a prebuilt family. I prefer the new Sim method because it's a lot easier hitting Bulldoze when you're done instead of individually selling however many violins individually. Unless you really hate the BFFs, then do your worst.