Mounting Electronics - Printing in Plastic: Build Your Own 3D Printer - page 290

Next, use three nylon spacers (1/2” or 1” depending on length of wood screw you choose to use) and
three #4 x 3/4” wood screws seen in Figure 16-5 to attach the Arduino.

■ Note You can use a fourth screw (and spacer) in the lower-right corner but you will have to file down the head

on the wood screws as it won't fit between the headers on the Arduino.

Figure 16-5. Use #4 screws and nylon spacers to attach the Mega.