Modelling Objects to Exact Size in mm

Hi I have been using blender for making game graphics for nearly a year now and I am thinking about making a new part (that will be printed in a 3d printer) for my gun. To do this I need to make the object with precise measurements in millimeters so that it will fit, is there an easy way to do this on blender or would I be better off learning CAD or some thing similar.

Go into the scene tab, and you’ll find a metric option under units.

I’m not sure if blender can be accurate enough for your needs.

Switch to metric, type in values manually when modeling. I recently printed off a bunch of models made in Blender without a hitch.