How much copper wire makes a pound?

That would depend on the thickness of the wire. Here is how you can calculate it:

Look up the density of copper. Use this to find out how much volume you need. Reminder: mass = volume x density.

Decide what diameter copper wire you want to use. Divide the diameter by 2 to get the radius.

Use the formula for the volume of a cylinder. Insert the known volume and radius, and solve for the length.

You may need some unit conversions. For example, if the density is given in pounds/cubic foot, and the diameter of the wire is given in inches, you would need to convert the radius from inches to feet.

If the copper wire has plastic insulation, the calculation of course is different.

You might also get data directly from data sheets, about the mass per unit length, for different wires.