It would be nice if placing walls and foundations worked similar to belts, i.e. click where you want the start of the item then drag to the desired end-point and click once more. The game calculates the material cost of belts based on length, so I don't see any complication with doing the same for walls and foundations. These items are particularly annoying since the player usually wants to place many foundation tiles or wall sections in a long line, all aligned the same way.