The hydrometer I have is 10in long and the fat part is 18mm diameter and 4.5in long then the skinny part it 8.5mm diameter and 5.5 in long. The print has very little wiggle room so I would do a test print to make sure its not too tight. I did put some little bumps and holes in the case so it clicks together with out slipping off. I just used PLA and it seems sturdy enough as my cat knocked it off the table and it didn't break the hydrometer or the case nor did it fall open. I just printed on the default setting on my Bambu Lab printer.