Today, I'm practicing with mesh gradients in Inkscape. Which are cool but damn, Inkscape doesn't exactly make them easy...
(Original silhouette by Andreas 06 on Wikimedia Commons; the cutting up into parts and 'texturing' is my work)
Next step is to have a separate 'shading' layer and 'surface' layer for each component, so that instead of a fixed white-based gradient of gray, it uses a partially-opaque-gradient black overlay to apply the depth illusion to *any* color choice (or even texture!)
I can arbitrarily recolor the plane now, without having to redo the gradients!
@joepie91 survivorshipbiascore