# Get a 3D model on this graph?

GROUPS:
 I want to do 3D printing on this graph. But the bottom does not have to be filled. Thank you for your help. ParametricPlot3D[{{t, 1/2 (1 - Abs[t] + Sqrt[1 - t^2]), 1/2 (-1 + Abs[t] + Sqrt[1 - t^2])}, {t, 1/2 (-1 + Abs[t] - Sqrt[1 - t^2]), 1/2 (1 - Abs[t] - Sqrt[1 - t^2])}}, {t, -1, 1}] 
 Thank you. I find this way. Improve it plz!! a = ParametricPlot3D[{t, 1/2 (-1 + Abs[t] - Sqrt[1 - t^2]), v}, {t, -1, 1}, {v, 0, 3 + 1/2 (1 - Abs[t] - Sqrt[1 - t^2])}, PlotTheme -> "ThickSurface"] b = ParametricPlot3D[{ t, 1/2 (1 - Abs[t] + Sqrt[1 - t^2]), v}, {t, -1, 1}, {v, 0, 3 - 1/2 (1 - Abs[t] - Sqrt[1 - t^2])}, PlotTheme -> "ThickSurface"]