I've made a dew of these to different designs, so forgive the mish-mash of photos in this instructable.
I make these up to order at www.zero-waste.co.uk
Step 1: What you need
1 x reel of thick thread, preferably synthetic and a needle.
A pair of scissors, pen or chalk and a ruler and square.
This .svg layout sheet
Some Dress pins
A sewing machine.
Optionally: sew-on velcro. (approx. 1m per badge)
UPDATE - Have had to remove the .svg file link from here as apparently it never worked! See the link above for the .svg layouts.