Unless you have a ridiculously heavy pendulum--and there *are* a few of these worth the excessive weight, or want to swing objects very dramatically, this sort of leather cord isn't ideal for precise dowsing since it's a little too robust, being 1.5mm thick.
However, the double fisherman's knot makes for great adjustability and hanging multiple tools. You get ample material length (37") if there's any need to combine and secure pieces in aesthetically weird (yet practical) ways. A bonus if oily skin is in the equation: the leather can be "conditioned" to some degree with decent maintenance!