cordage

I'm getting 2 canopy-anchors for heavy-duty rigging, one's the X Rings 3-ringed (2 large, 1 XL rings), 5', 3/4" sling, but that's crotches-only (unless I use a prusik or two to choke it, still waiting to find if that's OK to do!), but want to make something out of the Safebloc, the way I see it...

Hey everybody, this will be lengthy but hopefully it can help others looking for similar info. I'll also attach manufacturer downloads and helpful/relevant documents. I am looking to build a custom positioning lanyard similar to the Sterling Ultimate Positioning Lanyard and the Teufelberger...