Graphics3D[{Opacity[.5], Blue,
Translate[{Cone[], White, Opacity[.9],
Polygon[{{-1, -.25, -1}, {1, -.25, -1}, {1, .25, 1},
{-1, .25, 1}}]},{0,0,0}],
Translate[{Cone[], Yellow, Opacity[.9],
Polygon[{{1, 1, -1}, {1, 1, 1}, {-.5, -1.5, 1},
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Translate[{Cone[], Yellow, Opacity[.9],
Polygon[{{1, 1, .5}, {-1, 1, .5}, {-1, -1, .5},
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}, Boxed -> False, ViewAngle->.24, ViewPoint->{1.3, -2.4, 2}]