You will want some easily identifiable way to tell that your board has passed test. For standalone testing jigs, including a piezo buzzer and LED light are a simple way to indicate when a test has completed successfully.
For tests that take longer than a few seconds, adding a clamp to your tester design can greatly speed up your process by freeing up your hands to do other things while your board is undergoing test.
Adafruit carries a variety of the same clamps that we use in our own tester designs, including a variety of sizes and styles depending on the size and shape of the board being tested.
Order PCB: If you have the PCB design, want a longer-lasting tester, and don't mind waiting for a bit.
Mill PCB: If you have access to a milling machine and want to quickly and accurately create a prototype of your tester design.
Use proto shield: If you don't have the exact design for your PCB but have the general direction of how your tester will work.