1 x hi-vis vest, of the sort worn by roadworkers, and now, any kind of pedestrian or cyclist prone to being hit by a vehicle! These cost about £5, or much less in bulk or from an industrial supplier such as this one
. Most workplaces could get you some.
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.