The picture below shows the leather parts (first drawn on paper, then copied on the reverse side of the leather using the paper pattern, and then cut with small scissors) and a 15 cm zipper, which I narrowed a bit and treated the edges with Fray Stop.
Next step was to glue those parts together.
It is better to do this first and cut the zipper to correct length after gluing. Before cutting the zipper, I made a stopper by placing glue on the part of the zipper where I was going to cut it. To hide that, I glued a thin strip of leather over the end of the zipper (see pictures of finished boots at the end of this post).
The next step was making the insoles (cardboard and leather glued together in shape) and gluing the lower strips under them. This actually makes these boots fairly easy to make as you don't need to go around curves, if you plan the width and placement of the strips carefully.
Then I cut two narrow, long strips of leather (a bit longer than needed to be on the safe side; you can trim them in the end), glued their ends under the heel and trimmed and glued the rest of the strips to these vertical strips. This is fairly easy as you can make the boots tight fitting. There is no need to consider how you'll be able to get them off the doll's feet, because the zippers are there for that.
The leather I was using was thin, but I still decided to fill the underside of the insoles to get smooth outer soles and neat edges for the soles. The heels are carved from wood and covered with leather.
For the outer soles, I wanted something different, so I decided to copy Louboutin and used red leather.
Finally, here are photos of the finished boots from several angles.
An alternative way of making something like this would be cutting thin strips of leather and just wrapping them around the leg and gluing the ends to the edges of the zipper. That way, you could use very narrow strips and make intricate patterns. Of course you could also make intricate patterns with the method I've used, if you've got the patience to cut four pieces with a lot of little holes.
