When combining 2 items to create new item the original base item will not be used up, but will exist in addition to the newly created item.
Examples:
1. Combining a knife with an unpeeled potatoe will create the peeled potatoe without deleting the original unpeeled potatoe, meaning you can create an infinite amount of unpeeled potatoe with just the base potatoe as long as the unpeeled potatoe is not ruined .*
2. Combining Electrical repair kit with a protector case will create an improvised explosive without deleting the original protector case.**
3. Combining a knife with a raincoat to craft armbands will create armbands without deleting the raincoat they have been crafted from.