Here's a start. You can do a basic edge using:
- Solid Color source (with whatever color you want the edges to be)ill
- Slice Transform effect (add all your slices, Scaling mode Mask)
- Edge Detection effect
This will give you solid black shapes with edges in the color of your Solid Color source.
If the color is has red, green and blue each at either 0 or 100% (only primaries secondaries and white, ie full red, yellow, green, cyan, blue, magenta, white) then you can probably use Add(/Add50) blend mode to overlay other content, else you can try adding an Auto Mask effect after Edge Detection.
If any of your slices are touching, you will only be able to get an outline of the combined shapes, since there will be no "edge" between one shape and the other for Edge Detection to reveal. You can use multiple layers with non-neighbour slices, but this is probably a last resort solution.
You can see a complex example of this technique (using Radar to seep the edges) at:
https://www.facebook.com/groups/5854801 ... 736363277/