Just because it's crafted doesn't mean it can't be normally traded. Only those that were crafted using untradable items or metal make that item untradable.
For example, say you craft some scrap metal using an achievement weapon [a weapon unlocked from an achievement, which is "untradable"], making that scrap metal untradable. Using said "untradable" scrap metal to craft an item makes that item now untradable. See what I mean?
As long as it doesn't say "untradable", you can trade it. But those that are untradable, like say a Gibus, require gift wrap to trade it.