hello.

This tutorial will show you how to make a openable fairing, if your planning to make a fully reuseable rocket.
For this tutorial I will be using a Fuel Tank only.

STEP 1

Get a hinge rotator and put it where you want to open your fairing. Make sure the rotation is put to 45°.

STEP 2

Use the position tool instead of the moving gizmos. Make sure it is aligned with the fuel tank and still conected to the hinge.

STEP 3

After you aligned the fairing with the fuel tank build the base of the faring. Kinda like this.

Then make the radial Symmetry to 2x you should be done.
Something I did not point out is use cargo bays.