I bought the 2.5 inch lifts from shoelift.com and i quickly found out that they are unwearable. They are shaped like this.
and as you can see the sharp angle at the top dug into my heel and didn't fit the natural shape of my foot. I couldn't wear them for more than a few minutes before I was in severe pain.
But since i already spent all that money on them I decided i better get some use out of them.
So what I did was cut them in half like and put the bottom on top and the top on bottom like so. No glue or anything, just put them in the boot this way. The gap at the back actually acted like a hinge so they moved with my feet a bit
Then I bought a pair of flip flop sandals from old navy for 5 bucks and put this on top to smooth out the angle and better fit the curve of my feet. (blue layer) Then I added a layer of 1/4 inch foam (grey layer) cut into the shape of the inside of the boot (I used the original boot insert for a template) Finally I put the original insert on top. (excuse the crude diagrams)
It took a while to figure out how to get it all in there as it gets kinda cramped, but if you kinda roll up the toe ends, tuck them in and then roll them back out inside the boot it will go in just fine.
I then went to a cobbler and had extra thick soles added to the boots to give me another 2.5 inches on the outside heel. All in all it gave me 5.5 inches. So, being 6 foot, the boots and the added height of the helmet brought me all the way up to 6'8" with only a 2.5 visible sole and the capes and robe covered that well enough. I never got one single "Frankenvader" comment.
It was very comfortable and I could go all day with minimal sit breaks.