negative volume for concentric bottom fill

It's strange to upload a design that is not to be printed, even the opposite of being printed…

Use these to create an interesting fill pattern for the bottom layer, as shown in the images. This effect is achieved by applying a pattern of thin lines as negative volume, forming grooves dividing the bottom layer into small patches, which are then filled with concentric fill. I got the idea form Heliox, but thought it would be even more interesting with dual/tri-color filament, and also found that it doesn't need to be implemented in the model, but can be applied to any model using the slicer. 

Load a model, right-click → add negative volume → load → select one of these.
Infill → Bottom fill pattern: Concentric
I recommend  Advanced → elephant foot compensation: 0

Print with silk PLA for a shiny effect similar to brushed metal, or even dual-color or tri-color PLA for a sort of 3D-effect on the flat bottom layer. Best with smooth print bed; satin is still interesting, but somewhat matte and less shiny.

On a side note, Heliox called this effect ‘holographic’, like a couple of things are called hologram that aren't actually one; check Wikipedia on what a hologram actually is.