How many pins form the perimeter?

To determine how many pins form the perimeter, you would need to know the specific shape and dimensions of the area in question. For example, if it's a rectangular area, you can calculate the perimeter using the formula (P = 2(length + width)) and then divide by the spacing between each pin. The total number of pins along the perimeter would depend on how closely they are spaced. If you provide more details about the shape or configuration, I can give a more precise answer.