I first came across the rust paint effect on a course by Andy Skinner and the extra pitting effects from a demo by Diane Oliver at Tando Creative.
1) Dampen a greyboard ATC and mine into it with a pokey tool, dry
2) Paint over the whole card with Raw Umber, dry
3) Paint over the flat area with Weathered Wood crackle medium and dry
4) Paint over the flat area with cream coloured paint, dry
5) Dab texture sand paste onto the pitted areas, dry
6) Paint over the sand paste with Raw Umber, then dab Quinacridone Gold over the top
7) [Optional] Add dabs of Quinacridone Violet onto the rust areas.
8) Make a dilute wash of Raw Umber and Quinacridone Gold and go over the whole piece
9) Seal with Ultra matte varnish over the rusted areas and Glossy varnish over the flat areas
10) Stamp sentiment with archival ink and dry
11) Mount on a hammered card blank.

I have been drawing my own mandalas for a couple of years and have converted some to 3D artworks using laser-cut layers.
1) Draw concentric circles onto a grey art tile
2) Divide the circle with spokes (I used 16, I think)
3) Start drawing with a black pigment pen
4) Highlight areas with white pencil and white pen work