I read that thread and it's an interesting one but it doesn't really address my question. Still I re-read the rulebook and it's pretty obvious it's meant to work exactly like spare time rolls except you don't roll anything.

You have to be able to explain roleplay wise how you aqcuire your item. This part of the rulebook says it all really :

"The way you acquire and maintain equipment depends on your character’s skills and abilities. Resources is not necessarily just money but also the ability to maintain your own equipment. For instance, a wealthy Corporate has more money at his disposal; if some of his equipment is damaged, he simply buys replacements or already has spares on his spacecraft. In contrast, a Kaltoran mechanic may repair his own equipment, salvaging replacement parts to make it last as long as it can. Both the Corporate and Kaltoran may have the same Current Resources."

It doesn't state it outright but I guess you can infer heavily that you can't get a new weapon while sitting in a ship that doesn't have any possibility of having access to weapons.

Basically I'm thinking of scenarios where characters are far from civilization so they have to fend for themselves. In that case they wouldn't be able to simply change out items with a resource cost. At least that's how I'm going to rule it. Unless they have access to materials and a workbench ofc. Or an out of the way merchant they meet who first wants him to help them.