This is a step up from my MELO 4 tank. I can run the coils at a lower wattage without losing flavour or clouds, and the 4 ml capacity lasts me all day.
Only downer is that the swivel top comes open too easily, and I've had to deal with spilled juice in my messenger bag. I'm actually getting a collar 3d printed for it in order to prevent the swivel top from opening up when it's not being filled.
Other than that, I strongly recommend this tank. However, in case you want to make a collar, the inner diameter should be 22.5 mm, the inner height should be 6 mm, and the top hole should be at least 16 mm in diameter for the drip tip. Remember to account for printer tolerances :)