Center Tool
thingiverse
I crafted my own larger center tool since I couldn't locate one elsewhere. Hopefully, this creation will benefit others in a similar predicament. Simply place the device on any object with a uniform shape and voila - you'll have your center line in no time. It functions most effectively with circular and square objects. Does it work with other shapes? I intend to find out once I've printed it. UPDATE: I modified the outer edges by beveling them, which may enable the device to detach from the print bed without a catastrophic thermal explosion.
With this file you will be able to print Center Tool with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Center Tool.