The original Chopper is a great tool but didn't allow long pieces or scale rulers to be used when cutting.
Using the handle and screws from the original the RetroFitChopper offers a bigger capacity, Scale ruler (not included in kit) measurements can be me. Kit includes back stop, replacement sacrificial blade areas and removal fences.
Pictured above the 'General' brand ruler has N, HO, O and S scales which can be used with the RetroFitChopper making cutting to scale lengths a snap! $33.00