simplest AAA Battery Holder for your Caliper

Your cheap calipers drain batteries?

I know, I know, I know! There are already almost thousands of solutions for your cheap calipers. 

• There are plenty of battery covers (people tend to lose them when they try to preserve the battery from draining).
• There are “battery savers”, that try to disconnect one battery terminal while preserving the shape of the caliper. 
• There are coin cell to coin cell Adapters.
• There are additional Battery cases, that introduce wiring to replace the coin cell with an AAA or another AAA cell or even a Lipo cell.
• There is even the dead-bug style Capacitor solution, which gave us the insight that when the calipers are “off” they are actually still draining the battery.

Above are some very smart and minimalist solutions, I however present to you a solution with an actual physical “switch” for AAA cells that does not involve wires, only 3D printing.

This design is based on three things:

1. A friction fit between the Battery and the 3D printed tube
2. The fact that alkaline batteries have their positive contact right next to the negative contact. It is usually covered by an insulating label. 
3. A partial removal of above mentioned label that then serves as a switch. 

Update: please print Version 4:

Thanks to the positive feedback. I have tried to incorporate some of the suggestions. There are now 3 files available. You can chose between: 

• Caliper_AAA_Holder_V4_17… if your Battery lid has a width of approximately 17mm. Based on the downloads so far, I assume this file suitable for most people.
• Caliper_AAA_Holder_V5_15… if your Battery lid has a width of approximately 15mm. There is some variation of the caliper in the field and some people have reported to have a 15 mm wide battery lid. 
• Caliper_AAA_Holder_V4_17.1,1.2,1_EXPERIMENTAL_0.6mm-Nozzle.stl The name says it all. Some people reported to have issues with inserting the battery. This could be related to the wall thickness I chose. → If this file works, and the above does not, please report back!

Aside from the new files, here are some general remarks based on the comments: 

• The shape is purposefully not symmetric to give more possibilities to contact the battery terminals
• If you feel like scaling the whole thing: Please scale only in x-direction. That should only affect the fit of the battery but not the fit of the printed part in the caliper
• This only works for alkaline batteries. Zink-carbon, NiMh and lithiumsulfate need a wires to work properly. See the solution of Daafip here in the comments.

Preparation/Printing:

1. Partially remove the isolating label from the battery close to the negative contact. See the pictures for reference. Give it a “testfit” in the caliper to see if it turns on. 
2. Print the STL-File, it does not need supports
3. Insert the battery in the tube. It should be handtight. If it is not, you could either reprint, select another battery type, or (even more pragmatic) wrap the battery in scotch tape to make it thicker.  If it is too tight, you could cut off the upper part of the tube. (Or try V4_17.1,1.2,1_EXPERIMENTAL and give feedback)
4. Slide the AAA-Batteryholder in place and push on the battery so that it slides in the cavity where the coin cell used to be. 
5. Mark the on-position with a sharpie.
   
   Usage
6. Turn on/off by rotating the battery. You could also just keep it in the on position as the capacity of the AAA cell typically is way larger than of a button cell. 

Thanks to @moWerk for the request/support for the model adaptation for the 15mm version. 

This is designed for the models shown in the pictures, please have a look at the makes!!! The concept certainly is adaptable. Remixes are welcome. 

• A freecad file (Version 1, not shown in the pictures) is available,  as is 
• an Onshape Link to 17mm version / 15mm version