Mirroring symmetry


I have made an object that I would like to mirror but still keep it as the same object.

So far I have only been able to flip or mirror as a separate object, but not simple make a symmetrical object.

Is creating a symmetrical object possible?


Would just mirroring and unioning the two objects work?

I will give it another try but when I did it earlier it didn’t work properly, as there were still faces in the centre where it was originally mirrored.