These pieces help with making wrap bracelets like those sold by Chan Luu. They secure the leather and button to a standard 3/4" needlepoint frame making the weaving easier.
Print out one of each piece. Fill level or even layer height isn't that important. You may have to file out the grooves though to fit the leather cord. Measure out your leather cord and tie the button on it. Depending on the button size put it in the slot that fits best. The other piece will hold the leather. You'll probably have to secure both ends to the needlepoint frame with a little packing tape so it doesn't move around on you while you are working. You can find instructions all over the web for how to do the actual beading. An example is here http://www.instructables.com/id/Wrap-Bracelet/. My wife prefers beads with two sets of holes. Those are the ones you see in the photos.
Update: added two versions that totally encircle the frame (name has wrap included). These actually print fine with no support on my printer with PLA. They are more stable and require less packing tape than the earlier versions. The dished out part is put a thumb tack through to hold onto the frame better.