One using the laser to map out the tunnels surfaces with the addition of some light blade action to create the colourful swirls in the centre of the tunnel.
I used the 'Live Composite' function again to watch the progress as the image developed and is the result of multiple 20 second exposures over 16 minutes.(16 minutes at 20 secs f/8 @ 7.5mm fish eye lens)

Photographer: Stephen Elliott