I've made a couple now and they are easy peasy
Basically just cut out an oval shape for the base however big you want it, then cut a long strip of fabric folded over and wrap it around the oval to get the right length. I used tetron (sp) to put inside the 2 ovals to strengthen the base and a long strip of tetron inside the folded over length of fabric.
Pinned the llength of fabric (side) to the oval (base) and overlocked it together & voila carrier done.
However I used 2 lengths of webbing for the straps and sewed these to the folded over piece of fabric on each side then when I overlocked the whole thing the ends of the webbing got overlocked also
Not sure if any of that makes sense maybe I should do a tutorial for my next one and put it on my forgotten blog