connector for square profile

10x10mm internal 8mmOpenscad$fn=48;trubah_ext=10;trubah_int=8;connector_lenght=5;holediam=4;difference(){union(){translate([0,0,(trubah_ext-trubah_int)/4]){cube([trubah_ext,trubah_ext,trubah_int+(trubah_ext-trubah_int)/2],center=true);}//x-axis/*translate([connector_lenght,0,0]){cube([connector_lenght*2+trubah_ext,trubah_int,trubah_int],center=true);}*///dual xcube([connector_lenght*4+trubah_ext,trubah_int,trubah_int],center=true);//y-axis/*translate([0,connector_lenght,0]){cube([trubah_int,connector_lenght*2+trubah_ext,trubah_int],center=true);}*///dual ycube([trubah_int,connector_lenght*4+trubah_ext,trubah_int],center=true);//z-axistranslate([0,0,connector_lenght+(trubah_ext-trubah_int)/2]){cube([trubah_int,trubah_int,connector_lenght*2+trubah_ext],center=true);}}//ztranslate([0,0,connector_lenght/4+trubah_ext]){cylinder(h=connector_lenght+trubah_ext,d=holediam,center=true);}//small center holecylinder(h=connector_lenght+trubah_ext,d=holediam/2,center=true);//yrotate([-90,0,0]){translate([0,0,connector_lenght/4+trubah_ext]){cylinder(h=connector_lenght*2,d=holediam,center=true);}}//y dualrotate([90,0,0]){translate([0,0,connector_lenght/4+trubah_ext]){cylinder(h=connector_lenght*2,d=holediam,center=true);}}//xrotate([0,90,0]){translate([0,0,connector_lenght/4+trubah_ext]){cylinder(h=connector_lenght*2,d=holediam,center=true);}}//dual xrotate([0,-90,0]){translate([0,0,connector_lenght/4+trubah_ext]){cylinder(h=connector_lenght*2,d=holediam,center=true);}}}//capdifference(){translate([trubah_ext/2,trubah_ext/2,-trubah_int+(trubah_ext-trubah_int)*2]){cube([trubah_ext,trubah_ext,(trubah_ext-trubah_int)/2]);}translate([trubah_ext,trubah_ext,-trubah_int+(trubah_ext-trubah_int)*2-0.5]){cylinder(h=trubah_ext-trubah_int,d1=holediam/2-0.5,d2=holediam+0.5);}}