In order to build my cup, I gathered materials consisting of a plastic water bottle, a picnic cooler bag, a fluffy blue blanket, and a small, bendable, rubber tube. I deconstructed the cooler bag and removed the lining. This lining I would use as the inside of my cup and reshape into a smaller bag form for the liquid to go into. I would cut up the blanket into the same I wanted the cup to be and attach it to the lining. I the strap off of the cooler and attached it to the bottom of the lining/blanket.
I found a water bottle that had a detachable upper half. I disconnected the top half from the lower half and used a saw to make it a bit smaller. The top of the water bottle had a screw-on cap. I took off the cap and drilled a hole in it to insert the tube so that it would be part of the cap, and the tube would be the straw. Lastly, I attached the blanket/lining layer to the upper half of the bottle.