This Is One Of The Most Innovative Ideas I've Seen In A long Time
I think using rebar for the bar of a DIY bar clamp is a great idea.
That green coating on the rebar is an epoxy coating.
You can buy rebar with that coating already on it. Most local lumber yards won't carry it though. You might have to go direct to your local rebar supplier.
If you are going to deal with a rebar supplier, they will bend the rebar for you as well. You will probably have to put an order in and pick it up a few days later.
While your at it consider making some larger clamps with some thicker rebar. In addition to The 1/2″ (10M) for these smaller clamps you could go 5/8″ (15M) for medium sized clamps and 3/4 ” (20M) for large clamps. You could bend the 1/2″ rebar yourself, but the thicker the bar the harder it is to bend so why not let the supplier do it.
Watch the video to discover all the clamp building tricks.