I just had another look at the how to, I used leather on the pillars, not material, so mine would have been thicker, dont knock yourself out getting the edges perfect, they will be hidden by the strip when you put them back in anyway, make sure you have cleaned the pillars and even given them a sanding, this will make the plastic more abrasive and give it a key for the glue to bond better?? thats all I can think of right now
An important note.... cut with small nicks all around the edges, this will stop a lot of the creases you are getting, have another look at the pics, you will see after I have glues them I have nicked the leather all around, so when you fold it over again, there's no pressure on the leather, thats important