Rim strips are a bit of an overlooked item even when building a custom wheelset. You can use electrical tape that will stretch and probably rip, or you can use a cheapie strip that slides over, both exposing the spokes and leading to an unnecessary flat tire.
Our Avian $tripper$ Rim Strips are the answer. They're 18mm wide with heavy adhesive to prevent slippage and plenty thick so the rims spoke holes won't poke through. Available in packs of 2, or bulk packs of 100 rolls for bike shops.
66" long (per roll)