Proper sizing in blender?

Hi, I just downloaded blender today, after watching a dozen hours worth of modeling videos. I tried making a 3d model of a pistol and it either comes out too thick or too thin. Is it possible for me to set real world dimensions in blender? Like say 1 pixel =1 millimeter? I tried using the built in tools but it never comes out looking right.

Thank You.

You can set arbitrary units, metric units or imperial units in the scene settings


Like say 1 pixel =1 millimeter?
You don’t model in pixels but in dimensions.

If set to metric or imperial you will see the size of a grid unit in the top teft corner of the 3d view. Press N for the properties panel which will show the selected object dimensions

I tried using the built in tools but it never comes out looking right.
If it doesn’t look right it’s most likely not the scale that’s wrong but the object proportions https://www.youtube.com/watch?v=vh5kZ4uIUC0

Watching a dozen or two or even three dozen! videos is no substitute for reading the manual. Please do yourself a favor! and don’t rely on video tutorials, the majority of which show you how do a particular task without giving you any understanding of the underlying concepts.