J was using an old Nalgene water bottle, but after the BPA revelexplosion, he found these stainless steel bottles at REI. (I had one in green, but I lost it on the bus.) It’s not insulated, so it sweats in the summer and leaves rings on the table and is also uncomfortable to pick up, so I made a cozy for it. I wanted it to be open so the color could show through, but the holes are big enough for fingers to poke through also. Will need to try again.