This object is a part of an electric heater that I'm making now :) I had to make lots and lots of holes there. I found out boolean function can do the job but also found out it often ruins the vertex connections. I made a number of cylinders to make holes in the object but as expected it ended up making ugly meshes. Since boolean is considered not that easy for beginners to clean up edges and vertices, I also tried to look for any other way to make the holes such as knife but it either makes the ugly surface or it's difficult to duplicate the holes as many as it should be. Please help me with any solution. It doesn't matter if I should begin from the beginning or any other way. I appreciate so much!