square pipe conectors of any type 90*,cross,etc

Square pipe conectors of any type,angles,and ways to connect, they are build for 20x20 mm square pipe on the outside, and 16x16mm on the inside, but in the inside part i made it 16,2 that when inserted won t need screws to keep in place,it needs a little bit of force, and the depth that enter the square pipe i ve made it s 2 choices one with the depth of 21mm and the other one with 26 mm,i ve made it for test in PLA but it s better on petg or something better to be more resistant