Recommended Measurement Units - 3D print

When creating something for the purpose of 3D printing, which “Measurement Units” do you tend to utilize and at what precision?
There is a BIG difference between

Based on that choice, what do you choose for Length / Area / Volume

I have to assume using higher precision actually creates inconsistency with the final printing as the tolerances can’t match the model due to printer limitations. (but this is just an assumption on my part).

The Precision setting is only for dimension display. It has nothing to do with how precisely you can model.

Changing that setting doesn’t imply increased inconsistency in dimensions when you are 3D Printing.

The dimensions you enter need to be appropriate for the application.

When I model for 3D printing I model in Meters. I usually set Precision to four places beyond the decimal only so I can see those tiny dimensions to check for variations and such. I wouldn’t intentionally set dimensions to 4 places, though.

What if the print is something small like around 2" by 3"?
still start with meters?

I would. The .stl file will be unitless so it doesn’t really matter what units you model in. It matters what units you tell the slicer to apply to the file when you import it. I made these screen shots last night.

This is a model I did recently. The original was dimensioned in inches so that’s what I used but with Meters as the selected units. So the base of this thing is 3 in. in diameter.

And here it is shown in the slicer software. I selected Inches when I uploaded it.

FWIW, some people will model at the larger size and then scale down before creating the .stl file. You can do that if you want but since the .stl file has no units, I don’t know why you’d bother.

Thanks again for the help with this!
I am fairly new to SketchUp and 3D modeling, but the good news is, generally am a quick learner with most things.

I am trying to wrap my head around measurements and am probably making in more difficult than it needs to be.

I have already looked for online training or videos to cover this and fell short, but I will continue to look so I stop asking what I am certain are very basic questions.

Don’t agonize over it. For 3D printing you’ll be making models that are measured in mm or in. Set the units in SketchUp to meters and ignore the m. Or turn off Units display so you don’t need to worry about it.

Just a cautionary note.
This can be an issue in certain cases. Not all printer software has the ability to choose what units you want it to recognise. One of my printers is only metric and would be a nightmare to get accurate inches from a model in meters. So it is often easier to resize the model to what you want in inches then export it, the printer will read it as metric but it will be an accurate conversion of inches. You can export the .stl with the ‘correct’ units in the export dialog, but sometimes you end up going back and forth trying to get the right combination for your printer and it’s quicker to just work with the model. There’s no hard and fast rule, what works best for your setup is optimal.

For small objects I typically model 1000 times bigger to avoid SketchUp’s issues with small faces, i.e. set the model display unit to meter but interpret the numerical values as if they were in mm. The STL format lacks unit information, so you can export to STL using m as unit, and import specifying mm as unit, and the custom scale is corrected for.

Ideally SketchUp’s numeric precision, like when vertices merge and when faces are omitted, should either depend on the display unit, or be directly exposed, so you don’t have to apply any custom scaling.