Dude, if this thing needs 10 roboports to be crafted, the list it can give me back are my 70 robot slots I spent on it.
Also you could do a repairing kit storage for robots, where you have 70 slots for repairing kits (and of course this recipe gives you one of each, considering 10 roboports have a total amount of 70 slots of each type)
If you don't like the one-recipe-two-products thing, you can make a recipe for each one, both using 10 roboports, but in this case it would be fair that they had 100 slots, to compensate the loses (also remember this thing has no logistic or construction area, more loses to compensate)
Finally, if you don't like the repairing kit storage idea fine, don't do it, still this thing should have 70-100 robot slots to compensate loses, or, at list not having slot loses
