Get 10mg of luminol and dissolve it in 10mL of 10% ammonia solution, the exact concentration isn't critical. Then add 1mL of 3% hydrogen peroxide and dilute the whole solution into 100mL of distilled water.
Get a piece of copper metal, a penny will do, and drop it in with the lights out.
The penny will start to glow as the surface dissolves to form a copper amine complex. The complex catalyzes the reaction of hydrogen peroxide on luminol and causes the solution near the coin to glow. Bright trails can be seen if the copper is moved.
Eventually the concentration of copper in solution rises to the point that all of solution glows and masks the glow near the coin. The reaction will quickly extinguish as the luminol is used up.
It seems the reaction works best with copper. I wasn't able to get it work with iron.