Reading ring for tamp density measuring cylinder

Tamp density is a measuring method for powders, that gives the volume of a defined weight after a defined number of defined bumps. After tamping, the bulk material usually forms a taper inside the measuring cylinder, so you take the average of minimum and maximum. The scale is only on one side, though, which means you have to make an educated guess at which line would meet the highest and lowest point. However, if you put a ring around the cylinder, you can just move it to the right height and easily take the reading. We use an Engelsmann STAV II tamper with the original 250 ml cylinders – htey have an outside diameter of 39 mm.

There are two versions:
v.1: The thin clip is quite flexible. I designed it with 1.6 mm wall thickness, so that it is printed solid with a 0.4 mm nozzle and double walls and all fibres in bending direction.
v2: The thicker version is more rigid, because my colleague from the lab feared that during tamping it would slip down onto the slightly broadening base of the measuring cylinder and get widened over time. I wanted to keep the walls printed as double lines, so I increased wall thickness to 2.4 and put 25% infill between for improved stiffness.
...v3: A third version would only come if needed – but that is intended to have hooks for a small rubber ring that keeps the loose ends together. I don‘t have the motivation to go and ask maintenance for a rubber ring to fit the hooks to yet, so maybe i‘ll never get around to do the v3 design.