What would be better off for doing???

[Macattack64]

Using a Xacto Knife to splice the folds or use the red and black pen method.

 

[drgon47]

I think an xacto might cut through too easily. Either use pens, or if you have a knife with a angle like my crikit knife, then that works too.

 

[Digital Demise]

I think it is safer going with the pens because pressing to hard with even those can cut through the paper.
The key factor with the pens is that it makes the paper a little soggy and removes some material.
If you do go with the the x-acto look for a special head made for that purpose specifically because they do exist.

 

[MaShEdPOTaToEs]

i like using blue and red ball point pens with a ruler