module holder() {
difference() {
rotate( v=[0,0,1], a=-10 ) {
difference() {
cube( size=[4.2, 15, 8] );
translate( v=[0.6,0.6,0] ) {cube( size=[3,14.5, 8] );}
}
}
translate(v=[0,-10,0]) { cube( size=[30,10,8] ); } 
}

cube( size=[30, 1, 8]);

}

translate(  v=[-20,5,0] ) {
holder();
}

translate( v=[20,15,0] ) {
rotate( v=[0,0,1], a= 180 ) {
	holder();
}
}

translate(  v=[-20,-15,0] ) {
holder();
}

translate( v=[20,-5,0] ) {
rotate( v=[0,0,1], a= 180 ) {
	holder();
}
}