eleaf iStick mini slipover case

thingiverse

This is the best battery, but the threaded connection is weak and cartridges will pop out of alignment when it's in my pocket and gets bumped. The slipover case prevents this issue by securely holding the cartridge and battery in alignment, while remaining as thin as possible so as not to squander the device's delightfully small size. Mine printed fine at 0.28mm with no supports. Not a difficult print.