Mounting Electronics - Printing in Plastic: Build Your Own 3D Printer - page 286

Figure 16-1. Connecting motherboard and Arduino Mega
Push the pins on the underside of the motherboard firmly into the Arduino Mega; apply equal
pressure on all sides so you don't bend any pins. Before pushing completely in, make certain all pins are
being properly inserted into the Mega's headers (those black rectangles with little holes that line the
perimeter of the Mega). Figure 16-2 shows a side view of the motherboard inserted into the Mega.