I saw this “sandoe” or whatever compound word you can think of (Ruth Emily Davey “owns” the word “shandals”) in a leatherwork book from the 1970’s. It offers some special features:

To make the sandal, use the pattern to cut out two pieces for each sandal, flipping the pattern over to cut out the second  piece.

Punch stitch holes up the heel end of both pieces for each sandal, then stitch the two pieces together using the cross-stitch.

To make the ventilation slots on the sides, punch a round hole at the top and bottom of where you want the slots, then, with a utility knife against a ruler, cut between the holes on both sides.

Punch stitch holes along the bottom edge of the upper pieces.

Make your sole and punch stitch holes in it as shown on the pattern. To stitch on the sole, make sure you make a groove in the bottom of it to protect the stitching.

Stitch the sandal together.

Here’s a link to the patterns: https://drive.google.com/file/d/1g1gDkdzvgzKRR1TGDKW1R_I6N10oLN93/view?usp=sharing