If you ever need a replacement FFC for the Altair(-X), you can easily fold an off-the-shelf unit into the needed shape.
Find a FFC/FPC/ribbon cable with the following specifications:
An example listing for such a FFC can be found here - make sure to select the correct length (120mm), type (B), and pitch (0.5mm).
Simply fold the cable so that the short end is roughly 25mm from the end to the outer side of the bend, recreating the shape of the stock cable.