Frequently, even a conventional sandal is too hot for me, even in the winter. That's erythromelalgia for you. One way to retain the strength of a wide strap while allowing greater ventilation is to distribute the same load among many thinner lacings.
I like having decent arch and side support. Many sandals don't have this, and one is much more likely to twist an ankle, or worse, especially when working in low quality sandals.
Step 1: Ultra COOL Sandals With Arch and Side Support
I started with a pair of Birkenstock-knock-offs.
You know, the ones with a cork foot bed.
The straps were about an inch wide, and too hot for my feet.
I do, however, like the arch support, and the side walls that keep one's feet from slipping off to the side.
One of my friends refers to sandals as "German safety shoes" LOL. The support of these sandals is really helpful though, when lifting heavy stuff. In my experience, knee problems and even back problems can start in inadequate foot support.
Step 2: Cut Off Straps
Here's a picture of a Birkenstock sandal. Cut the straps off.
I don't think they'll have copyright issues with my using the picture. After all, I'm advising you to buy new sandals, and immediately void your warranty.
Leave enough leather to punch holes for the lacing.
Scissors were adequate for me.
Step 3: Punch Holes
I used the smallest setting of my pliers-type leather punch.
But a hammer, nail, and block of wood would suffice.
Do a lot of holes. If there were only a few laces, the forces would be concentrated on just a few holes, and more likely to tear out. I didn't even count or measure, just made the same number of holes on each side of shoe.
Step 4: Lace 'Em Up
I used thin elastic cord. This allows some give without going through a complete re-lacing every time.
I do re-lace the ankle part,each time. This helps prevent sandals coming off at inopportune moments (like backing up while carrying a steel I-beam or somethin)
Depending on ambient temperatures, and the dress code, I may wear these with no socks, white socks, or black socks. I'm only wearing one black, and one white in this picture to show you the options (honest!!)