Extending DiscretizeRegion from 2D to 3D [duplicate]

I am trying to construct some 3D printable parts using discretized regions, and am curious if there is a good means to transform a well-designed 2D region into a corresponding 3D region extended straight in the z-axis (e.g. triangle to prism). It seems that using the 'same' methodology to make a 3D region causes a severe loss in resolution compared to 2D.

rs = 1;
n = 10;
rb = n*rs;
p = ((rb - rs) {Cos[\[Theta]], Sin[\[Theta]]} + (rs) {Cos[n*\[Theta]], -Sin[n*\[Theta]]});
P2D = ParametricPlot[p, {\[Theta], 0, 2 \[Pi]}];
R2D = DiscretizeRegion[ParametricRegion[r*p, {{\[Theta], 0, 2 \[Pi]}, {r, 0, 1}}], MaxCellMeasure -> 1/10, AccuracyGoal -> 10];
R3D = DiscretizeRegion[ParametricRegion[{0, 0, z} + r*Append[p, 0], {{\[Theta], 0, 2 \[Pi]}, {r, 0, 1}, {z, 0, 1}}], MaxCellMeasure -> 1/10, AccuracyGoal -> 10];
Row[{P2D, R2D, R3D}]


• The curve is self intersection at the corners. It make the 2D region more complex. Commented Jun 24 at 10:08

RegionProduct[R2D, Line[{{0.}, {2.}}]]