I installed a horizontal conduit under our house. I shoulda included a draw string in it at the time.

Rather than pull it all out and thread a draw string in, I did this:

• Got a length of builder's string
• Tied a stubby steel screwdriver bit to the string
• Fed the bit and some of the string into the conduit
• Used a neodymium magnet from an old hard drive to drag the bit along inside the conduit

Worked a treat!