//50mm width seems good in your hand //70mm length seems good in your hand //20mm high is more than enough //central holen needs to be 8mm mounting hole //the knob is 45mm in diameter at the base scale([.9,1,1]) { translate([-25,0,0]) { scale([0.3,1.114,1]) { difference() { translate([15,0,0]) circle(d=70); translate([70/2,0,0]) square(70,center=true); } } } mirror() translate([-25,0,0]) { scale([0.3,1.114,1]) { difference() { translate([15,0,0]) circle(d=70); translate([70/2,0,0]) square(70,center=true); } } } square([50,70],center=true); }