They are scattered in multiple locations, mostly back at my parents house. I have too many slings to keep with me 

I still have the very first braided sling I made (in sisal) very short and messy but in fairness it worked pretty well.

I wouldn't actually say there has been a giant improvement over the initial gains from the first 5 or so. There are many different variations and experiments though.

Making a great feeling natural sling still feels about 50% random chance to me.

Most of the sisal wisdom I've picked up is that you should soak the sling after braiding (doesn't have to be for long), then dry under tension to avoid stretch. This makes very tough but great feeling cord with lowish stretch. A nice tight braid is also helpful of course.

Thickness I find quite important too, the sisal I work with is quite thick and the difference between 6, 8 and 10 cord thickness is very noticeable. I once made a 10 thickness (base- max was 2x thickness) balearic which was very nicely crafted (possibly some of my neatest work) but the combination of being quite thick and a bit longer than average for a balearic sling (closer to 30'') just made it a drag to use, it was hard to get enough power into the shots and just didn't seem to work well (probably my technique as well).

Another fail was I recently made a very long 45'' balearic, but it had been so long since I made one that it didn't turn out so great- the pouch split wasn't thick enough or something so it drops rocks constantly, and the release knot/grip is just not substantial enough when launching big rocks as I am apt to do with long slings, so accuracy goes out of the window.

Basically, there is still a lot of improvement/experimenting to be had 

Still, both are at least nice decorative pieces