Lithoscope Mark 1

function main() {
   return union(
       difference(
        cylinder( {r1:10, r2: 35, h: 40, fn:4 }),
        cylinder( {r1:10, r2: 35, h: 40, fn:4 }).translate( [ 0, 0, 4 ]),
        cylinder( { r: 8, fn: 4, h: 10 } )
        ).rotateZ( 45 ),
        cylinder( {r:8, h: 1, fn:4 }).rotateZ( 45 ).translate( [ 12, 0, 0 ]),
        cylinder( {r:8, h: 1, fn:4 }).rotateZ( 45 ).translate( [ -12, 0, 0 ])
);
}