It's totally understandable - this stuff is SO sticky, so it can eliminate a lot of the problems with using sandals as approach shoes. And to answer the question I already see forming in your head, yes sandals can make great approach shoes, even for epic climbs like the Northeast Face of Pingora. The best part is that they are easy to carry up with you on epic routes, whereas carrying even light approach shoes can be a real pain.
The major problem that Five Ten rubber presents in making minimalist sandals is that it is thin - so much so that it is floppy. Not cool if you don't want to trip on it. The solution to this is to use Barge Cement to glue leather on top of the Five Ten Rubber, which will serve to make the sandal more comfortable and less floppy. Again, you can use Barefoot Ted's instructions to cut the sandal out appropriately and a Leather Punch for creating the holes. The heel holes can be cut with two small leather punches and a razor blade that cuts straight between them.
Despite the photo shown above where I used paracord, have come to enjoy using thin tubular webbing on my sandals the most - it is very strong and tends to be soft enough to be comfy, and the thickness of the material means that there are no major pressure points as long as you tie the sandals correctly. A really awesome source for webbing that comes with a buckle already is Bedrock Sandals Straps! Check them out! Another alternative to the webbing is Luna Traditional Ribbon Laces.
Lastly, lace up your sandals just right. Luna has tips on this, but as I mentioned above I prefer to use a buckle on my sandals. This allows me to simply tighten them down and go. Most importantly is you must adjust the laces to fit your preferences - for me I like the webbing to lay as flat and un-twisted as possible against my foot as to prevent chafing. Experiment with it! \
When you are done, send me a photo of your beautiful creation. What are you waiting for - get out there, feel the wind on your toes and the earth beneath your feet, and do something awesome.