As you can see in my images, all of my cubes are inaccurately placed on this object and the four corned cubes (labeled as blue) are not placed accurately on the on the corners of this object. Is there a way to accurately space out the difference between each cube, for example I might want each cube to be placed 2 cm apart from each other, and I want all the four corned cubes to be placed precisely on the corners of this object?
How would I do this for this particular situation?
Use snap vertex and an array modifier. By snapping a cubes vertex to the outside edge of the castle turret the cube will be lined up. Then add a array modifier to that cube and set the count to 4. If your math is right number 4 cube will line up with the opposed edge.
This may not be the way you would do this on the spur of the moment, but it might illustrate a couple of methods you can use in other places as well.
With Pivot set to 3D Cursor, and snap set to target > vertex and source > median, as shown...
Using the knife tool K and constraining it to the center of edges by holding down Ctrl, cut a line between 2 mitres.
Create the appropriate number of edge loops across that face: CtrlR, Scroll the number of loops, and left then right click to exit without sliding the loops.
in object mode, move the cube in XY (G,ShiftZ). Holding Ctrl as you drag enables snap: move your mouse over the leftmost new vertex on the frame to snap the median of the cube to its XY.
ShiftD the cube to copy it (or AltD to make an instance), and before any other operation, ShiftZ to constrain the duplicate's movement to XY. As before, snap the duplicate's median to the next vertex along your guideline.
Then ShiftR twice, repeats the last action, creaing the next 2 cubes.
Now, select all 4 cubes, ShiftD, and RZ 90, to fill the next side.
Lastly select all the cubes. ShiftD, and RZ 180, to finish. (Delete your guidelines).
