How do you get sandbox in btd5?

In Bloons Tower Defense 5 (BTD5), you can access the Sandbox mode by selecting the "Play" option from the main menu, then choosing "Sandbox" from the game modes list. This mode allows you to place any towers, set the starting cash, and control the flow of bloons for testing strategies without the pressure of losing. It's a great way to experiment with different tower placements and upgrades. Enjoy testing your setups!