1st person arms still clipping with near plane 0.01

I have the two cameras approach already. So it isn't the problem with near plane being set too close.

So, you're already using the 2-cameras approach - this should solve your problem! Since it isn't, something else is wrong: the closer near plane is being set in the wrong camera, or something in the code is restoring the original 2nd camera near plane, or the main camera is rendering the player too and hasn't a lower depth etc.

Let's check the basics: create a new layer (let's call it PlayerBody) and move the weapons and the player body to it; create a new camera (remove its AudioListener) and set the fields Depth = 1, Clear Flags = Depth Only, Culling $$anonymous$$ask = PlayerBody, Near = 0.01; child this camera to the $$anonymous$$ain Camera and reset its position/rotation. In the $$anonymous$$ain Camera, the only change is the Culling $$anonymous$$ask, where everything but PlayerBody must be marked. Check these settings carefully - they always work fine, thus you must have missed something.

Thanks for your answer, but I double checked everything and it is set exactly like you mentioned. Could it be some kind of problem with the 3d model?

No, this is clearly caused by near plane clipping. Try to eliminate suspects one by one. For instance: while the game is running, disable the second camera in the Editor - the player body should disappear; if it doesn't, the depths are wrong and the main camera is covering the second one, or the layers are incorrectly set and the player is being rendered by the main camera. If the player disappears, then the second camera's near plane must be the culprit. Pay attention to public variables: the Editor keeps the last values set, even if we change them in the script - if you're setting the near plane to the value defined in a public variable, it may be keeping some old and incorrect value.