Hello I'm really new to blender and have built my first model, a block of flats... It's made of more than 1700 different cubes that stick together their way so that it could be one only model or mesh. But it dont have snapped perfectly to grid while I was building this are millimeters on the most zoom that aren't Stick together and there are faces over faces leaning on other faces. So what i want is snap all that objects perfectly to grid in all dimensions and delete the faces that are leaning over other faces and unite all objects perfectly to one only 3d model mesh. I don't would like to do that by hand with boolean union 1700 cubes Everytime one with another so what can I do ? The grid is on 0.125 meters and i want it to have a such a resolution i want every vertex to be exactly sticking strictly perfectly to one straight grid and to get rid of the overlapping faces... It is a very symmetrical model but complex It is for game development and performance reasons.
Select all objects go to edit mode, in mesh editing join by distance keep join the distance really small.
To do this you might need to first create one object from all the objects by joining them (ctrl +j). It depends of the blender version you use if you can edit multiple objects at once.