How do you create a new backpack cover?

[LucienNL 90]

Sometimes I can, but most of the times I can not create a new Lv.2 backpack cover. It says I do not have the required materials. That doesn't make any sense to me. Did anyone figure this out?

[reiner- 504]

In a safe house.

Go to customise backpack and you'll find it there. 

Make sure you have the available materials. 

Edited November 19 by reiner-

[LucienNL 90]

1 hour ago, reiner- said:

In a safe house.

Go to customise backpack and you'll find it there. 

Make sure you have the available materials. 

I know that. But sometimes it gives me the message that I do not have enough materials. All catagories are at 0. What materials is it using? The ones you have stored at your facility? Because buildable safehouses do not have materials stocked. I just don't understand why it's giving me a message that I do not have enough materials when all my wherehouses and facilities are maxed out. I am very close to the platinum trophy so I have all the materials in the world.

[reiner- 504]

Well then best to use a room at one of the main hubs like those large buildings with Bridges on the side it.

Unless you recycle items or materials there won't be any available materials to craft with.