Handle for carrying water bottles

A handle for carrying 5- and 6-liter bottles of water. 

There are two things I don't like about the standard handle: firstly, only three fingers fit inside it. Secondly, it has sharp edges. 

Both of these problems have been solved in my handle: there is room for a fourth finger and the edges have been expanded and smoothed. I now have bottles at home with two sizes of standard handles; mine is suitable for both. If the standard handles of your bottles don't fit into the groove or if your palm is significantly different in width from mine, simply scale my model down slightly in a slicer along its length.