Cardboard proved to be interesting material, so I had to experiment a bit more. Here are shoe soles for Jessica Rabbit (who has Tonner's Athletic Body with high heel feet). These are similar to the Barbie and Monster High shoes, except for the curved part in the heel.
Here the soles have been painted with gold paint.
I decided to make the insoles the same way as for the orange silk shoes. The main thing with these is to make sure there is glue only in the parts that go under the insoles, so the fabric stays neat. Also, be careful when cutting the triangular flaps. There should be no cut edges visible on the sides of the insoles.
I glued little loops for the straps. When you do it this way, you can glue the insoles to the outer soles before putting the straps in place, which makes things easier. Also, you can change the straps to different ones at any point, so you get a very versatile pair of shoes this way.
Finally, here are the finished shoes. You can vary the material, length and positioning of the straps to get different results.