First, the code you’ve been given won’t work with your current setup. Handles only function when they are descendants of a players PlayerGui or the CoreGui. You will need to put the handle in startergui, set the adornee to the part, and put the script inside the handle.
Second, to check if a part will be exiting the bounds, you will want to get the positions of each corner, using the parts size and manipulating its cframe, then convert that into a position. You will need two vector3’s for the bounds, and will need to check if each corners position is within those bounds by comparing the X,Y and Z values to the values of the bounds.
There is nothing wrong with the script, you need to add your own reference to the handles instance. This is normally assumed. Here it is setup for you. Baseplate.rbxl (13.3 KB)