How about this idea for combining:Anson wrote:and an additional "repair by combining" tool could be researched that (only on demand) compresses a damaged stack to a corresponding healthy stack with fewer items.
You place (or find) a damaged turret on the ground. Then you take another turret in the hand and place it on top of the damaged turret. The health of the turret in the hand is added to the turret on the ground. If there is health left over you keep a damaged turret in the hand, if not the turret in the hand disappears.