I've added a new filter
Repair / Solidify in the G'MIC plugin for GIMP that should be quite equivalent to the Flaming Pear Solidify filter.
Attachment:
gmic_solidify.png [ 386.9 KiB | Viewed 5732 times ]
The solidify algorithm is also used in another filter, namely
Artistic / Smooth abstract :
Attachment:
gmic_smoothabstract.png [ 481.02 KiB | Viewed 5732 times ]
I've also recorded a small video to show how this Solidify filter can be used to quickly create color gradients with complex shapes.
If you have some time to play with it and get interesting results, let me know !