For these I used a table lamp fitted with a red bulb for the first shot, and a blue one for the second. The lamp has a variable in-line dimmer on the cord, so I was able to turn the power down very low - enough to illuminate the element, without blowing the light area of the shot. Each one was formed from six manually focussed shots stacked in Helicon.
Why? Haven't got a clue. C&C welcome.