DIY Akton pads

[beginner skater]

Hi there
I live in the UK and have managed to buy one pair of Ultra Crash hip pads. I can't find any more for sale, so I have ordered some Akton pads, so I can DIY my own, an idea I got from this site. I am planning on protecting hips, knees and tailbone. And maybe if there is left overs, some small pads sewn into a headband.

Has anyone got any tips? I am not sure whether to shape the DIY pads to the hip ones - they are thinline hip ones, but are marked with the word "knee".
I am not sure as to the best way to finish the edges after I have cut them, and whether to go for simple rectangle shapes, as being easier to finish off.
Thanks for any help