I made a set of tools for micrometer experiments, one for each student, and one that can be organized into groups of four students (and can also be stacked and moved around).

*The one at my previous school was an old micrometer set, and many of the schools I have worked at and checked had the same model. Therefore, it was made based on the size of that micrometer, so the size may not match newer ones or ones made by a different company. Please understand that.

★Background to creation
In Japanese high schools, micrometer experiments are a staple of biology. (I don't know about the situation in other countries...)
"Objective micrometers", "ocular micrometers", and the "caps" on the telescope tubes used to set the ocular micrometers - these small items are distributed to the students' experiment tables and then collected. Even if you arrange them in order when putting them away in drawers, they quickly fall apart, and you have to rearrange them again when distributing them.
This kind of miscellaneous work is so troublesome... I had been planning to make a set for a long time, but the only options were paper craft and other models, so the work process was difficult and I was unable to make them. However, in 2024, when a 3D printer (Bambu lab P1S) was introduced at the high school where I worked, I decided to try making them with a 3D printer. This is my first attempt at 3D data and 3D printer modeling.
Since it was my first time, I had no know-how and made many failures, but I managed to create a set for 44 students and 11 groups, considering the basic 40 students in one class in Japan, plus the occasional students who were held back in the same grade.
Unfortunately, I only made them and was transferred to a different school in April of this year, so I was unable to use them in actual experiments, but I was able to confirm that transportation, collection, and storage have all become much more convenient.

★ About the model
The 3D data was created using "Tinkercad".

・Case
At first, I made it as one part, but it took a long time to make because it needed supports, which used unnecessary filament, and because the shape was complicated.
So, for this upload, I remade it so that it could be separated.
When actually using the micrometer, the objective micrometer is only needed initially for the calibration process, and when actually measuring cells or small objects, only the eyepiece micrometer (and the cap of the telescope tube) is used, so I think it would be a good idea to separate the objective micrometer and distribute only the top part. (I don't know if there will be a separate experiment to measure actual cells. At my previous school, we only taught how to calibrate the micrometer, and only students who finished that task quickly measured the length of actual cells, etc.)
By making it a separate version, the support was not needed as intended, and the modeling time was also significantly reduced.
However, since the strength of the separate version has not been confirmed with an actual objective micrometer inside, will it be able to be firmly fixed with the objective micrometer inside? Conversely, will it require extra effort, such as removing the objective micrometer, when removing it? I have not checked these things. (My current school does not have biology experiments, so micrometers do not exist in the first place.) I have not put anything inside to check it, but I have confirmed that it fits securely, is fixed, and does not break.

Just to be sure, I have also uploaded the stl of the original one-piece version of the original body that I created.

*All photos that show a micrometer inside are not of the separate type. Only photos that show the case by itself are of the separate type.

・Tray
I will verbally instruct students to always put the cap on when removing the eyepiece micrometer, and I have written this on the tray as well. (The text can be changed as needed, but there are four places on one tray, and two rows, so all of them need to be changed. If there is a setting that will result in the same text, I would appreciate it if you could let me know. I am still learning.)
At first, I made holes all the way to the bottom of this note to reduce the amount of filament used, but since the text can break and it takes a lot of time, I did not make it all the way to the bottom this time.
The tray numbering is based on the desk layout at my previous school, so please change it as necessary. (Please let me know if there is a sequential number setting for this as well.)

It took a long time to design the hinges and to find a shape that would allow them to be stacked, but it was worth the effort, and I am very satisfied with the result because they can be stacked securely and easily separated when distributing.

・Handle
The handle can be used to lift up stacked items, but if it is used alone it will bend and I am concerned about its strength. (As shown in the photo of it being lifted up)

So I also made a handle cover. With the handle cover, it is strong and does not bend. It is a simple item that you just insert, so I don't think there is any need to make it a structure with strange two-color printing or supports. (When I created it, I did not know that Bamubu Studio's function had automatic rotation, so I went to the trouble of creating my own support and created it sideways. However, I now realize that this is not a strong structure, so I have left it in its current state. It takes time, there is a risk of it falling over, and it does not require that much strength in the first place, so I will upload the one I made if necessary.)

I have not checked whether it can be stacked more than that because three was enough for the number of stacks to carry around, given the height of the drawers I put away. Three can be carried with ease, and you may be able to stack more, but please be careful as they are valuable items. And, of course, please understand that I cannot take responsibility for any damage.
When stacking and carrying them, please be careful as they are designed to come off easily if carried roughly and may fall off.

★Finally
I would be very happy if this helps you, even a little, with your experiment preparation and cleanup.
I made this only to make my own work more efficient, so it may not meet all your needs, but I hope you will forgive me for that.

*The text was translated from Japanese to English using Google Translate. I'm not good at English, so I don't understand if the sentences are different from my own intentions.