Mine is not to stiff.
If you want a sling that you can wrap your front hand around then I would say the final product may be to thick.
I could have made one as well. I have made watch bands and bracelets.
Since he was offering a choice of colors, as well as the connectors and the matching band to allow me to make it adjustable, I figured for the price, I could not go wrong.
It would have cost me at least $20 or more to buy all the stuff and get it shipped here.
If you have all the materials and the time then I say go for it.
At least if you dont like the final product and feel that it is to stiff, you can untie it.
When you make it please post up some pics of it.