IWISS Ratchet Spark Plug Wire Crimper for Spark Plug Ignition Wire and Terminals Dia. 8.5mm I bought one off Amazon for $25 shipped. The first time I tried making my own custom length plug wires and it could not have gone better. There are many positive reviews on Amazon. I highly recommend these. https://www.amazon.com/gp/product/B07K2VG6XY/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1