Holds 550 paracord. There are a bunch of these out there, but I found the other designs lacking.

This holds 100 ft of cord.

This uses normal rectangular razor blades (aka scraper blades, Stanley 11-515).

This is .2" thick and doesn't flex.

This has holes in the middle for attaching the bitter end of the cord.

This has notches along the sides for melting the tag end into a nice shape.

Blade guard is not flimsy.

Blade cover snaps in place and doesn't need screws. Feel free to glue it shut if you wish.

Usage:

Slip cord through top middle, tie overhand knot, pull into slight recess on bottom. Wrap tight.