This is an articulated wrist mounted cup holder designed for the Within Reach Design Challenge. It allows people with minimal use of their hands to pick up and set down cups. It is designed to allow the cup to rotate forwards and backwards for stabilization purposes. In order to wear the wrist mount, you just need to have a Velcro band. There are 2 sizes for the wrist mount: normal and large. The normal one is not as stable as the large one, but it prints quicker and does not take up as much room on your arm. It uses 3/4" Velcro straps. The large one is mores stable and uses a 2" Velcro strap. A cup does not have to fit perfectly. Most cups in my kitchen fit in this cup holder.  However, if the cup holder does not fit your cup, you can just print the scalable  version of it and resize it to the correct dimensions in your slicer of choice and then just print and glue on the knob. In order  for this to work correctly, you do need the strap to be tight enough. If you are still having trouble with the strap, try putting something stiff on the back side of the strap, use less liquid, a lighter cup, or a smaller cup. This design allows the user to easily pick up cups and set them down without the use of their hands. If you wish to see it in action and hear a more detailed description, just watch the video I made at this link ( Articulated Wrist Mounted Cup Holder For The Within Reach Design Challenge)