I´m pretty sure it may work... maybe you can take the mechanical parts of a regular pull down ladder and adapt this design... I think the problem will be about the space you need... the size may be as much as the double compared to a regular pull down ladder... so you have to make sure the hole in the roof must have the right space.Instead of having steps of 4 inches...like in a regular pull down ladder... you need at least 8 inches for this design to work safely.Hope you try it!
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