I made a "Zehner", which is what the Germans call a string of ten large beads, fairly early in my collection career, because it's such a typical type of rosary/paternoster, especially in all those 15th-century portraits. (See Counting to Ten for more examples.) The way I first made it was ridiculously easy: I just took ten linked beads from one of the several wall rosaries I'd bought on eBay, added a cross to one end and a ring to the other.
The way I put this together was not terribly authentic, so I decided it needed an upgrade. Also, one of the beads had gotten chipped. Wire links are not a common technique for this type, and a couple of years looking at period crosses told me that the one I'd used (because I happened to have it around) wasn't a very good candidate either.
The beads are machine carved, and difficult to string because the holes are large and conical, much bigger at one end than at the other. Adding small black wooden beads to fill the overly large holes makes it possible to use a string of normal size. I chose hemp this time, partly because it seemed plausible for a not terribly costly set of wooden beads, and partly because I had black hemp string in an appropriate size on hand.
The cross is something I got from Rosary Workshop, and I've been looking for just the right project to use it on. Like a lot of Rosary Workshop's pieces, it's from an undated original, but most of their pieces are cast from 19th-century originals. This particular one is Greek, and shows Mary and the Infant Jesus rather than the usual body of Christ on the cross. The four roundels at the ends of the arms appear to contain angels, though it's hard to tell (such portraits are sometimes the four Evangelists instead). A lot of Rosary Workshop's pieces are "primitive looking" like this, so even if I can't justify them as accurate reproductions of anything medieval, they look the part.
Here's another detail of the remodeled Zehner.