With how many perimeters and infil is it recommended to print the armors?

My comment on that would be weight. I used a piece of my WM armour in S3D and looked the difference in weight between 1 outline and 10% vs 3 outlines and 0% It was 150g difference for approx 1/6 of the chest, that's getting up to 1kg for the whole piece You start adding that up and by the time you've done a whole suit, that's a lot of extra weight. Yes, 3 outlines will be strong, but you have to balance strength vs weight and whether the part you're printing is going to be under stress when wearing it

@Funkster S3D weight calculations are consistently 20 to 40% over estimated. I'm recording each part and my research shows this.

CR-10 SUNLU PLA+ Sanding not been a problem with either. Not go to the sanding stage on War Machine yet, but I have done a First Order Snowtrooper (the helmet wasn't printed), nearly at the painting stage of a First Order Trooper I do use a few coats of automotive 2K filler primer, so that will help make up any loss through sanding