Linhof 6X17 close up lens

I have a linhof 6 X 17 with a grand angulon 90, and was wondering if their was a close up lens or filter available anywhere for this lens. It sure would be nice to get closer than 5 feet. Thanks,
John

I don't think that there is a close up lens for use on a LF lens as this kind of lens usually uses bellows draw for close up photography. And using a close up lens on Linhof is not practical either - how would you focus the lens? A hyper focal distance is not useful in close up photography :>) and the gg use for Linhof is limited too.