<p>I am wondering if making an hermetic box is feasible using 3D printer. The box would be a cube with a front face removable, with screw and sealing joint to close it.<br>
I searched for different materials, however, none talks about hermiticity. (However, I found a product that seems to improve water resistance of 3D printed items <a href="http://www.nanovia-technologies.com/...mperm-f10-ft-tds.pdf" rel="noreferrer">here</a>, which might be a starting point)    </p>

<p>Does anyone have experienced to make hermetic things ? I am specially interested in carbon fiber reinforced materials.</p>

I believe this can be achieved using o-rings.  That's what they use for scuba diving lights.  The component doesn't need to be circular, but the o-ring needs to be slightly smaller than the component so that it is held in place via tension.  Additionally, you'll want to create a groove for the o-ring to set it in and make sure that the o-ring protrudes slightly so that it applies pressure and creates a tiny amount of friction when it's coupled with its counterpart.  Apply some type of lubricant to prevent the o-ring from sliding out of place and to keep it from drying out and cracking.