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This is a modified (upgraded) reproduction of the part used in the 90's Doctor Who pinball machine. Since this is the modified / upgraded version it has section baffles between each sensor to remove the sensor problem that people are experiencing These baffles also ensure the new channel is solid cancelling out any warping. Search "swinkswho?" to locate the alternatives to this part as well as other parts.
The original parts were injection moulded and have stresses within the part and due to the length these typically warped and then some don't function properly. Even some of the in stock ones at some part suppliers are warped from new.
With these ones being 3d printed (laser sintered) there is no tension in the part and therefore no warping before you even install it.
Note 1: The BLACK Natural Versatile Plastic dueis a little more textured than the polished and dyed versions, which may mean running a drill / round file through a couple of the target or sensor holes if needed.
Note 2: reports have back from a few people and they can confirm that these function well with the only requirement to ever so lightly run some fine sand paper in the mushroom target holes and then fully functional, not warped and cancels out IR LED light from optos from neighbouring optos.
ps - big thanks for the help and hand model - @pinballinreno :)