I had a laser job last week for an electrician. He needed some tags made for a job he was trying to finish up on. These plastice tags mean things to them and are needed to pass their inspection by the state electrical inspector.
They have standard sizes and colors they use. They will give you the wording for the signs. They also know the code for the colors and sizes they need.
I spent this weekend making a flyer and some samples to mail out to my local contractors. The research I did tells me plumbers, electricians, HVAC installers, fires systems, security systems all use these tags/plates.
They sell for $3-$8 a tag. It's really good money.
I've included my master templates so you can just drop your text on the tags. These are the most common sizes they use. Take a look at the flyer and you will see a list of the most common colors they use.
I've got an order of 40 tags coming next week from a contractor who says it's very hard to find a source for the tags.....