I'm going interstate for a few days, I should still have net access, but just in case I don't feel free to set up the roll for the stretcher without me.
Incidentally, which primary attribute would be most applicable? I'd think Mind, but part of me also says the dexterity of body might be applicable. Scavenging skills would apply to it, as would anything where you arguably have to improvise such crafting. (Both Thief and Repair could apply)
DC would be 15 if you want the stretcher to last.
Personally, I'd say Mind is more important than Body. And if Grease is the one building it, then I'd say Mechanic would apply, but not Repair.