Wow, “lock” up shopping carts with a homemade “portable yellow line”… debate in the comments!
Ever noticed a painted yellow line in the parking lot around many supermarkets and retail stores? The magic yellow line emits a signal that causes carts to stop dead in their tracks, preventing carts from leaving the parking lot.
Now you can build your own portable yellow line– with up to a 20 foot range. Need I say more? Hint: it works inside the store.