26650 to 18650 battery adapter

Adapter to use 18650 battery in place of a 26650.

Test print last night and it didn't quite fit. New upload has slightly larger ID and is a little shorter. I reduced the height to 60mm so that the battery will stick out the end a little. I also made the ID 20mm. Apparently an 18mm battery doesn't fit in an 18mm tube.

v2 has an ID of 19mm. The 20mm was a little lose for my test battery.

Th 19mm is too tight a fit for one of my batteries (the red coated one)